My "evidence" is I've been to conventions and got a photo with him, I spoke to others in the line and heard about their previous experiences with him before. I've read Doohan's biography, other coworkers, I've heard Shatner himself (online)., Maybe you guys have had different experience where Shatner has had a chat to you in the autograph line or even just said "Hello" as you get a photograph. LOL.
I'm not saying Shatner is a bad person. I'm not someone he has personally wronged. And the worst I heard said of him was that he was basically rude. Not that he ruined anyone's career or anything like that. I reckon, Harrison Ford and Carrie Fisher probably have the same feeling about their fans and their stupid questions that Shatner does but are just too polite to say so.
You know Takei and Doohan may have just been "day players" but deserved respect as human beings. Saying that - Takei could just let it go after 40 years. Thats why I'm suspecting the "feud" is just something made up to create interest by both of them.
Co-stars tell-all books are probably the least reliable. The authors had an axe to grind and it comes off as whining from minor league actors who didn't escape typecasting and had their egos inflated by fans at conventions over the decades. Besides, books saying how awesomely everyone got along for 500 pages won't sell as many copies.
Personal experience is a little better, but fans do tend to be bothersome, even at events specifically made to give us an audience with the stars. Some of the stuff coming out of people's mouths is just incredible. But okay, they are at a table to meet the folks who watch them all the time and helped make them famous. Everyone has a bad day. Of the actors I've met, here are three who I have had bad experiences with:
Robert Vaughn
Herb Jefferson Jr.
Lou Ferrigno
They all have great reputations for be cool to talk to. But at the moment I reached them, something was bothering them and I walked out with a bad memory. Maybe they were tired, or the convention organizers pissed them off or maybe they just ate bad tuna for lunch. Whatever. I doubt highly any of them thought I. or any of the fans. were "scum."
Every person I know who has met Shatner recently, especially at the Ticonderoga events, relates a hugely positive experience. If he thought fans were "scum" and hated Star Trek or something, he wouldn't be showing up repeatedly on a recreation of the sets to meet people. He certainly doesn't need the money or the gig.