If he knew, he crossed a line.

You are supposed to roast people for their choices, not their medical conditions. (And yes, you could argue that she could have worn a wig, but I respect her a lot for NOT choosing to wear one...as half the women in that room probably were. Little known fact, it's fairly common for actresses to have very short natural hair because they are doing work which requires wearing a wig and, speaking from experience, getting a wig over long hair is annoying).

So yeah, I do think he was out of line and here's the thing?

If he didn't know, it's still on him, because he should have done his research on the nominees and their plus ones before roasting them, and Pinkett Smith has been very open about this.

So either he crossed a line or he didn't do his research, and I hope he has learned from that and will do better (and funnier) next time.