The much broader and more general problem is anything that could stem from a lack of appropriate boundaries between faculty and students. Sexual assault is just

The much broader and more general problem is anything that could stem from a lack of appropriate boundaries between faculty and students. Sexual assault is just a worst case scenario in that category of problems. You are of course correct that someone who would do such a thing shouldn’t be teaching, but it’s much more reliable and pragmatic to simply have reasonable rules and boundaries than it is to determine with 100% accuracy what people are capable of. Not just to prevent the possibility of sex scandals, but to prevent the entire category of problems from being more of an issue than it already is.