It should not be contingent on the other passengers to restrain some kook.
The flight attendants need to be trained to do it and any that don’t feel comfortable doing so don’t need to work for the airline.
I don’t think we are getting the full story yet.
Crews are trained in basic self defense. MMA classes are not part of the curriculum.
Aircraft are equipped with flex cuffs. I suspect the reporting on this is from a tunnel vision viewpoint. The crew “disappeared” to report it to the cockpit, get the flex cuffs, and gather able bodied assistants to subdue the gentleman.
Just because you don’t see something happening doesn’t mean it isn’t happening.
EC