The Station fire is an alleged act of arson. It may be confirmed after a trial, though even courtroom verdicts are open to doubt, as illustrated by an article in the current New Yorker:
http://www.newyorker.com/reporting/2009/…

I think if there's no mention of Bumbershoot it's pretty reasonable that there was also no mention of PAX.

Dear non-nerds: we are talking about this expo: http://www.paxsite.com/ put on by the local comics-makers and gamer-geeks of Penny Arcade: http://www.penny-arcade.com/