I think that he wanted to return to the stage in a fairly low key manner, as he had done previously with Delaney and Bonnie. Given what the press did to him in 1974 I doubt that he would have wanted the publicty that would have surrounded a tour of the US, or even Europe.
He liked to have Clapton around him when he played live, and it's also possible that EC had other commitments, thereby preventing any other shows.
Just a theory.