I'm not following with how a different campaign environment makes the negadungeon a good thing. Perhaps it's because this scenario keeps playing in my mind:
DM tells the players about a horrible negadungeon by having characters in the campaign refer to it as a terrible place and warning the players not to go there.
Players subsequently don't go near negadungeon, so you designed something thst never came up.
Or
A player suggests going to the negadungeon to check it out... or something. The rest of the players start asking "but, in character, why would we go where people keep telling us not to go?" Since there is no sane response possible, everyone drops the idea and they go to a posidungeon instead.
Or are the players not supposed to know it's a negadungeon until they finish it?