Just because two people are adults doesn't make a relationship between them not dodgy; think about how bad it is for a doctor to date a patient. The situation here isn't quite as bad (well, if you start stalking a former student after they break up with you, I guess one could also argue that this case is much worse than some other situations where everything unfolds amicably), but still, relationships between people in power and those over whom the power is wielded are not just socially frowned upon, they are recognized as Bad News (if not always strictly illegal) for a long time now.
I'm not sure why you're so insistent on defending if not a sexual predator then at least someone with highly questionable judgement. And again, maybe all of this has little to do with the whistleblower stuff, but there is no question about whether or not it's true that she had an inappropriate extramartial affair with a student, stalked him after he tried to end it and was fired over the whole ordeal.