The trouble is, you’ve made a lot of this stuff up.
If the scenario was as you’ve suggested, of course there’s a problem!
But there’s no evidence that much of what you say is actually the case.
This in particular stands out too:
He gets off on the dynamic, on the memories, on the fact that she was his student and the prospect of making her uncomfortable now, he knows it's inappropriate and that's what he likes.
If he gets off on the dynamic and his memory of her, that’s entirely his business (assuming a proper gap between her leaving school and now). You’ve then yoked it seamlessly to the bit that is a problem - the prospect of making her uncomfortable. But that bit is conjecture.
If he’s doing that last bit, if he’s deliberately sought her out and wants her to know it, that’s the problematic bit.
What I object to is the pointless demonisation of the sexual thoughts themselves. It’s happened a lot on this thread by many posters.
There was someone who said they didn’t want a man who masturbates over young women anywhere near her children. As if the aim is to eliminate other people’s sexual fantasies! It’s not only ridiculous- it’s counter-productive.
Male behaviour is a massive problem in our society. It’s an unmanageable problem at the moment tbh. It leaks into all our culture. It needs constant policing. There’s plenty to do without speculating about what men might be masturbating over FFS.
You don’t know, even, if the guy is a ‘known creep’. There are plenty of teachers that kids label ‘creepy’ without a shred of evidence. Equally, there are plenty of genuinely predatory men who go under the radar.
I’m sorry if this topic is bringing back specific memories for you. But this is not about your predatory teacher.