This teacher and student have both left the college. ...
Nothing else matters from what you wrote.
They're gone; it should be as if they were never there.
The college has no
say in the matter.
PS Unless I had signed some sort of nondisclosure or similar arrangement which would cover the time after I had left a company (and at least in the US, the enforceability of such agreements is truly suspect, as they tend to be what's called a contract of adhesion
), then I would be appalled by any former employer trying to dictate what I could do after I left their employ.
If GDPR or the like applies, then maybe things are different.
And either way, you should be talking to the school's legal department about this. That's what they're there for.