As is a common catchphrase of mine in Terry tickets ; if you are having issues with securities behaviour I suggest you admin help rather than seek revenge. Particularly when most peoples idea of a response to 'person did me wrong' is to yell shitsec and grief the whole department (see your previous ban). You are not the overseer of security, I am. However your previous ban is not on appeal here, if you felt it was unfair then you should have appealed it, by not doing so you accepted the judgement, which means you'd be expected to learn from it and the point you were actually banned for being the collateral death you caused.
I'm not banning you from using foam, if I were the ban would read "Is prohibited from using foam". You can do what you like with foam, but you will face the consequences of your choices.
KILLING INNOCENTS is the problem here, you need to rebase your arguments around that, I don't care if you foam down an antag, I'm probably not /too/ bothered if you burn things in medbay lobby since there's nothing there, sure I'll raise an eyebrow at you because self defence AOE weapons are really just banbaiting yourself, but it's the consequences for the other players that matter. And all you care about, consistently, is your own experience. Again you need to adjust your perspective.
Excessive control? As per the ban in all caps the simple exercise of control here is to /NOT BUILD AND USE AOE WEAPONS/ as a non antag. If you wanna play die-of-fate with escalating bans then thats on you, you CAN NOT kill innocent players, if your weapon is not suitable for those conditions then don't use it, same as we enforce sec to use non lethals on non antags, and if you forgot to charge your baton, tough, go charge it. It's like you maxcap the station and kill 20 people and then complain that its unfair of me to ask you to control the maxcap. You THINK you can control what happens, you maybe even TRIED, but you just cant, there are too many variables and every time you do this is a crap shoot on wether you'll fuck it up and get banned. Literally choosing a weapon you can not control to that degree. And thats why I call this banbaiting yourself, do it enough and it's guaranteed to go wrong. Same with health sensor activated small explosives ; maybe it works twice, maybe the third time a spider eats you on the shuttle and you cop a week ban (actual case).
And re the teleporter, sure, why not be liable, you're the one that decided to turn a safe location into a hell hole. Hell, how about seeing the person who just teleported in as someone who might HELP YOU rather than just some potential liability that might get you banned because AOE. What exactly is your mindset going into this game, because as a non antag you're "another person having another day at work", by the book, meanwhile you're beginning to sound obsessed with the need to AOE down rooms. Have you thought about what you're doing? From a roleplay context, not from a gaming context ; you're a person who thinks a reasonable self defence mechanism is to scorched earth the room - does that sound like a sane, normal, behaviour? You're guilty of manslaughter at a minimum, all sorts of other sundries around incompetence, negligence leading to others death and so on, and I'd argue perhaps even murder because it's so obvious something could go wrong. Regardless you're probably going to jail or a psych ward. Why are you so fixated on trying to use AOE weapons. You were the captain/only command, you've got the contraband locker, two overpowered guns from cap+hos, armor, grenades, stun batons, cargo orders for guns, everything in the armory. Don't go nuts and jump the gun and turn into a walking armory before any threats are particularly revealed but esp as captain you're very much welcome to be armed with a reasonable selection. Why on earth do you need a hellfire grenade. (Edit: oh yeah and that OP sword with the huge block chance thats perfect for common garden melee fights)
And yup, some tot fireaxing you is not a round ending threat, no matter how much you'd like to spin out the fact that you're critical to the round and the tot is just going to kill everyone and win. Which given that its 4 pop if they just go murder everyone i'm probably gonna speak to them and ask them not to go murderboney on such low pops as it will just empty the server (and whats the point in 1 pop tot station <insert link to setting up a private server>

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I suggest you play it safe, just quit it with the AOE gimmick, its not that hard, everyone else manages it. But thats not the rules, you can do whatever you like with foam and AOE stuff but you will be liable for the consequences, heck, i'll note (or worse) players if they go blow up the refuelling simulation with zero casualties other than themselves, simply because it only serves to space rec and destroy facilities that others might care about (or suffocate from). It's the collatoral that matters. But since you're slowly coming to the realisation that this isn't as controllable as you'd like, including your speculative teleport example, you can see why this cheap room destroying weapon is only really used by antags, everyone else either sees the ban trap, gets banned and reforms, or gets permabanned. It's just kinda natural selection, this behaviour inevitably weeds its self out because its unsustainable, you WILL fuck it up no matter how much you try. Hence my genuine advice to you is to stop trying. But its the side effects that are the actual rule break so I'm /not/ enforcing "no aoe" "no foam" "no whatever else", just that i'll ban you even harder next time you fuck it up. What you do with this conundrum is your choice. I think it's pretty intuitive, however we're still arguing this after two bans and an appeal so big ole shrugs from me, nice as it is to educate you on the what and why I'm not required to reach that goal, I just like to try.
Anyway, still not budging on this one, and I'm pretty sure you're not going to get me to give ground here. I don't seem to be getting through to you, you're not taking into consideration a lot of key factors in your arguments, in fact you only seem to be trying to argue out a path that lets you go AOE things down more. And i'm not stopping you doing that, though I think it would be a poor choice for you to experiment further in this field, that is your choice and your future, no particular investment of mine.
I don't intend to keep debating this with you, I intend to reject this appeal and close this out, the only response at this point I'll react to is you asking for this to be escalated to the headmins in which case I will kick off the due process, otherwise if you do not request this within a few days, or confirm you don't wish to escalate, I will close this appeal as denied.