Again, I recall them making changes in tone and removing classes like the assassin (I think they also took out the half orc as well). I think those changes were not great. I enjoyed 2E for its settings, and I think the system worked well. But it did suffer in terms of the tone (to me it felt like an extension of the blandness that had crept into so much 80s entertainment). Which is one of the reasons a setting like Dark Sun was so refreshing.
I know for example the removal of the assassin almost resulted in Artemis Entreri being taken out of the books too (and I believe RA Salvatore had to make a case that he wasn't an assassin but a duel or multi class character---fighter thief or something). So there definitely were substantial changes.
But again, I don't recall any actual ban on evil player characters. It is possible I missed this and just have overlooked it all these years. I wouldn't say cautioning against evil pcs is the same as prohibiting them.