How come Nick Bockwinkel didn't wrestle in the WWWF during the Sammartino era?

Answer 1

Because he didn't want to leave the AWA and play second fiddle to Bruno

Answer 2

I think he would have been booked to lose, and I don't think he would have gone along with it.  Bockwinkel DID wrestle Bob Backlund for the WWWF title, though (credit to Bob Backlund), and the match ended in a double countout.

Answer 3

Bruno had him blackballed because he knew he would get his assa kicked by Nick Bockwinker. He was a huge politician and diva backstage just like Hollywood Hogan