I made my point, and he now knows beyond a shadow of a doubt that I'm closely monitoring him.......and I am.
I had told him that I'm far too busy in my work to have to take a day out for such a thing....and that it should be unnecessary......but I was VERY prepared to do just that. I gave him concrete suggestions of things he should be teaching that are matters of historical fact and, therefore, not as subject to his interpretation.
The slightest hint of a relapse and I'm on 'im like white on rice. I've taken on his Principal and a couple of idiotic English "teachers" there before without blinking, and I think he knows it.