Thank you!

I think that from all we know about Sirius, it is safe to assume that he was not merely difficult but was suffering from a psychological condition.

Let's remember, what he's essentially said is, "Gee, I wish your chronic illness were in an acute phase right now."he who makes the depreciating remarks first, others will assume that it is no big deal for him and won't try to hurt him by throwing werewolf insults into his face. That's at least how I see Remus.