Frankly, I couldn't care one iota if, a) there are mixed opinions, or b) whether any one individual "buys into" face masks. When you "buy into" travel on public transport you "buy into" the rules and regulations in place at the time, which haven't been put there by Bill Gates, an alien from Mars or those pesky Ruskies, they have been put in place on advise from the WHO, and also by most experts in the field worldwide; and yes, I know you'll be able to point to scientists you say the opposite, just as you can to scientists who don't believe in man made global warming.
If you wish to use such services you obey the rules, and frankly a diversion of a flight, or halting of a bus or train is perfectly reasonable if people refuse to work to the rules. We hear that cabin crew feel unable to enforce instructions handed down by the airline for fear up upsetting people, if that is the case then a couple of burly (unarmed!) sky marshals on flights prone to misbehaviour may be a solution. I don't know if Simon Calder was correct to the letter of the law, but he said this morning that instructions from the aircraft commander must be aboyed under the Air Navigation Order. That being the case the covidiots don't have a leg to stand on.