I personally believe it's prudish and uncalled for, she did nothing illegal, she was in the army, got out did some porn, went back in got out did some more porn, went to school got her bachelors and education certificates. She has no criminal background or she wouldn't have gotten her teaching certificate in either state.
I'm with Bettingpython on this. She did not break the law. No asked, "was she a good teacher?" As an outside observer, I do not see anything to indicate that her past was somehow adversely affecting her job performance. I am sure that some kids might have gotten into their old man's stash of videos (assuming anyone still has VHS) and found her out, but I still do not see how that would warrant firing her.