a) This was a hate crime done by someone who really, REALLY hates furries or
b) This was done just for the lulz by someone who didn't aim to kill people but just to close the convention and troll furries?
Because commonly the punishment is greater for hate crimes, but if someone does something like this for FUN doesn't that make it clear that person is a danger to everyone around them?
(Note that this is just speculation on the subject and I have no idea on what the actual motive was this time.)
It's conditional on a few other factors, but I would say the punishment should be harsher if it was a hate crime* rather than "trolling".
Reason: Someone who actively hates group X and wants them dead is an active danger against group-X-ers in any situation. Keeping them behind bars were they cannot try to kill people again is probably the only way to stop them.
Someone who thinks it's a fun joke to leak chlorine gas in a convention is an idiot, but has
some hope of redemption. Presumably if shocked sufficiently harshly they can realise they were being an idiot, they should recalibrate their idea of "joke", and then go on and live their lives without recklessly endangering other people.
Like I said, conditional on other factors. Maybe the idiot is so much of an idiot they don't take this incident as a wake-up call. Maybe the furryphobe can learn their lesson and stop trying to kill people. But I find those to be less likely scenarios.
*not sure if the legal definition of hate crime fits crimes out of hatred of any group or only some specific ones. Here I meaning specifically a crime motivated by hatred of furries.