Ahhh see the thing is there is no way they can legally stop him from performing the song OR recording it. He just has to pay the piper (or the venue must) BUT sampling a mechanical construct as in a recorded song and placing it in a new mechanical recording MUST be legally cleared first with the mechanical rights holder.
So in short I can legally use a melody and/or lyrics that have been published without getting permission to either perform it live or make a new recording, I just need to pay the fees to do so. However using a mechanical recording is different. I can use it in a live performance and it works the same way as above BUT if I use that mechanical recording in a new Recording then I must clear it with the mechanical rights holder first and if they deny it I can not legally use the sample/recording and can lose the rights and all profits from selling a work with an unauthorized sample of a mechanical recording but still be liable for all the production costs etc. And even owe a large sum of money if it gets pirated and I make no money whatsoever.
Anyway, my point was that Kid Rock shared the publishing with Skynard and Zevon, and doesn't that mean they share in the royalties? He did right by both of those artists, unlike many other musicians do. BTW, could Skynard have sued Zevon since the beat, tempo, and I believe bass line in "Werewolves" were the same? Guess I still don't get your explanation.