There are a few thieves around. However, according to the few thief posts I've seen, you are only allowed to steal certain items from certain players. Seems the "community" on Siege Perilous demands some sort of insurance for events and new players.
On one hand this "community" bashes production shard players because they have insurance. However, on the other hand, they quickly lash out at those who steal from members of [NEW] or players participating in EM events. Stating that it's in bad taste and that those thieves are bad/newb/dumb/ insert some other derogatory comment. What they should be doing is educating those [NEW] players on the risks of Siege and not blame the thieves for doing what thieves do...stealing!
That, my friend, is your state of the game for Siege Perilous. But, if you're indeed a thief, sounds like there are quite a few dumbasses on the shard keeping lots of items in their packs... might be a good time to take those items off their hands