You are required to wear gloves in a chemistry class for your own protection, and such a requirement isn't contrary to school policy.
> As it was, what she was doing was personally putting him in danger.
No, he was putting himself in danger by choosing to be in an environment where he was exposed to lots of other people, knowing full well that he is at the highest risk of severe illness or death from COVID because he's elderly and has comorbidities.
> Of course he has every right to demand whatever he wants in his classroom.
Really? So he could ask students to segregate themselves into seating areas by, say, race or religion? Vaccination status?
It would be ok to require gloves for her own protection, which is outside and in addition to school policy, but it’s not ok to require a mask which protects everyone and is also outside of and in addition to school policy? That’s your argument?