This is purely conjecture on my part with no refrences, but maybe he was happy with it at first but then peer pressure set in about being on such a show and then he turned against it. People do change their minds about things.
I mentioned once in a previous thread about some actors going uncredited because they didn't want to be associated with the show and I was promptly shushed, but not everyone had a positive image of science fiction in general at that time.
Your conjecture is just as good as everyone elses and please don't let anyone get you thinking otherwise. I may not personally agree, but I applaud your diverse point-of-view.
As to your specific theory, could be. He may have gotten opportunties in the interim between doing the pilot and the call for a second one. It's plausible and I had not previously considered it. Thank you.