Trying to muzzle a cat would only result in the cat trying to frantically get the muzzle off their face - cat's aren't very tolerant to such things.
For a cat who doesn't like brushing it would be better to slowly acclimate them to gentle brushing instead of using force that would make them hate the whole event and possibly you.
Nothing to be afraid of. Maybe it would be best for you to start with a soft bristles brush - like a baby brush and let your cat get used to rubbing their own cheeks on it? Then do a little brushing/petting.
Also, some cats don't like certain types of brushes. The ones that are like a mitt or rubber like a zoom groom seem to really feel good to cats.