The article discusses at length a systemic cover-up of Epstein's involvement with the Media Lab. Multiple high-level people knew about it, knew that MIT had deemed that donations from him were not welcome, and tried to keep his involvement hidden. In other words, they knew they were doing something wrong, and they did it anyway.
From this, it is clear that some people were "seriously tainted" by Epstein's involvement.
Is there a question of where to draw the line? Sure. We don't have have all of the information, so clearly we can't draw a line. But when OP says
It strikes me as inappropriate to suggest that "Anyone seriously tainted by Epstein should step down". What does "tainted" mean? What does "seriously" mean?
the clear argument is that, because drawing a line is hard, we shouldn't call for any action against those who have stepped over it. That's an insult to his many, many victims and provides cover for his enablers. Honestly it's an affront to women everywhere.