Seriously though... the less he gets mentioned in-game, the better. I don't think it can be avoided entirely as he has become canon or am I mistaken there?
WotC have a flexible (and from discussions here, sometimes controversial!) approach to canon. There's not one set canon that all FR media need to follow, and just because one licensed source does include Abdel, that doesn't necessarily mean others also have to or even necessarily have to be consistent. I think they see each D&D game/book/etc as a kind of possible world that might have various things in common with other games set in the FR, but exactly how much is mainly left up to DMs and players to determine. So in this case, I imagine Larian would have had a fair amount of leeway in how far they took things like Murder in Baldur's Gate as part of their own story. My guess is that they might have taken some elements and probably haven't done anything that completely and obviously contradicts it, but that they've left enough open that a wide variety of BG1&2 playthroughs would still be consistent with what we learn in BG3. At least, that's my hope!
BTW The FR wiki has some useful stuff on the approach to canon
here.
