There were definitely opportunities to have sex in BGII. More or less graphic depending on your hero and choice of who you slept with. However, being primarily text-based it was not visually graphic. I'm not old enough to know if that was considered controversial at the time and have no desire to check on the internet, but I would venture to say there is a large number of people who enjoy the romance options. Especially when looking at the numbers Larian posted about EA romance.
However, I will say that their idea seems to be that you can more or less opt out of it -- unlike one of the dragon age games where a friend of mine said she was playing and saying nice things and her chick ends up in bed with another chick and had no idea how it came to be. As for the nudity, I personally don't care. I can see the appeal for a filter (say you want to play the game and there are underage children in your house), but it wouldn't be something I would use.
But back to the OP statement. I don't know how old your son is. I also don't know what you consider soft-core. However, if it's just topless women, I can see that on a PG-13 (13+) film, but it's an M(17+) rating in video games. Either way, if you want/need to censor what your son plays, then I suggest you do research on forums for parental reviews prior to letting him purchase or play a game. I imagine you could have a discussion, set boundaries, and play Co-op, but if not then that's up to you. Best of luck.
