There are two muzzles - the sanctioning body's, and the sponsor's.
When I see/hear clips of drivers using colourful metaphors, then we'll be getting somewhere!

BTW, I have to confess that I had to look up the year of the Allison-Yarborough fight.

"I got out of my car and all of a sudden, Cale's nose started beating on my fist." - Bobby Allison

Now that's NASCAR!