No experience to share except to say that being irritated - and being irritated in an IOP programme - seems to be pretty common.
Most times people putting other people down, especially in an early recovery setting, is a way to mask their own insecurities and worries, as well as a form of bonding with others - however distasteful.
My advice is to befriend those who seem on the outer. No matter what kind of insecurity fuels it, asshattery is asshattery and you don't have to condone it.
Congrats on 30 days
D