No one has actually said he abused them, just some college group saying he had sex with college students. You know... consenting adults.

faculty are prohibited from entering into a sexual relationship with any student or postdoc for whom the faculty member has any responsibility for supervision, evaluation, grading, advising, employment, or other instructional or supervisory activity

There is no evidence he had sex with students of his, because again, no one has actually accused him of abusing them. If someone comes forward and said he abused his power over them then there's a problem, but that hasn't happened.

All of this is happening 3 weeks before his primary against a 32 year incumbent Wall St ghoul.