I am reasonably certain that Price would have sooner invited Tom Kennedy and Doug Davidson before they even so much as considered Barker being involved.
Well, see, that is
a problem: to most of the people watching the show, it's Barker, not Carey, not Kennedy, and certainly not Davidson, that they associate with the show because of his longevity with it.
I don't think it was a conspiracy, either. It's blatantly obvious that the intention was to spotlight the contestants, which even highlights what Barker said in one of his oft-repeated soundbites, that it was the contestants who were the stars of the show. There's nothing wrong with honoring the contestants and designing an anniversary show around some of the more well-known or better-remembered ones.
I think there would be something very wrong with intentionally setting out to snub Barker. (I don't think that's what happened in this case at all, but I think if they set out to do that, it would have been wrong and the criticism would have been justified, no matter how much of an iron fist Barker ruled with when he was the boss.) At some point, show runners have to set aside their own feelings and prejudices and focus on their audience. If they would have set out to do a show that needed Barker's participation just so that they could willingly ignore him, they wouldn't have been considering their audience, and that would have been a mistake.