"that she has indicated to governors that she will stick by him so long as he shows "unequivocal repentance" for his crimes, then I see nothing to indicate that children at her school are at any increased risk from her presence than they would be without it."
This is the woman who had no idea of his activities before. How exactly is she going to know if he stops being unequivocally repentant this time? He didn't exactly advertise his tendencies before, did he?
You don't need to fear that she will let herself be manipulated into actually helping him take illicit photos. All you need to fear is that she will, in a few years time, be tempted to let him come with her to the school fete or pick her up at school one day or let the children she teaches know that he is Miss' husband but fail to include the other piece of information.
I do not for a moment believe that she will knowingly let herself be manipulated. But if she believes in his repentance, then she will be open to being used as an innocent tool. If she believes in his repentance, how long will she go on policing him? Standing up to him and reminding him why he is not going anywhere near her school. Watching everything she says so she does not inadvertently betray any information about any pupil which he could use to gain their confidence? Year after year? While she believes in his repentance...