You yourself said you don't know why he deleted them. So how could you assume that its not because of temptation to drink?
Obviously he has some problem with having them as friends to just delete them. Even if it was an impulse decision. It made him feel a certain way that he didn't like. Enough to do something about it, too.
I know for me, if I deleted my friends because reading their posts made me feel something I didnt want to, yet my bf still had them as friends, it would bother me (Depending on why I deleted them). If it were mutual friends, then hey, I'd have no say so. But if he met them through me, doesn't see them unless I'm there or because I take him, then please respect my feelings.
It'll feel like my bf is at a party with all my friends, and I'm home, sick.
I think what you should really be doing is asking your H whats going on. What's he feeling and why he wants to seperate himself from his friends. His answer might make it easier for you to understand why he's asking you to do this for him. You'll never know why or understand, until you communicate with him.
Best luck to you..