I'd be inclined to agree, if that was her crime. But, it wasn't.
This teacher was arrested for sex with a student. (That student also happened to be a minor but, that's beside the point.)
It's entirely reasonable for parents to expect that school faculty and staff will not engage in sexual relations with their kids under any circumstances, regardless of how "hot" anyone may be.
This isn't a simple hook-up between consenting individuals. This is someone who violated her position of sacred trust.
That’s dumb. Can her, ban her, but don’t arrest her.