Sometimes dogs act differently at the groomer than they do at home or even at the vet. Dogs still can breathe with a muzzle on, in fact they can still bite with a muzzle on if they really want to. It may be worth it to try.
We get a lot of dogs in that the owners can't get near their nails, but we can do it fine. We have a very few dogs that just never seem to get it and that it takes a few of us to do with the dog muzzled. Maybe just call the groomers or go visit and talk to one in person to see what they think.