I came away from that interview honestly wondering if Brooks had early onset dementia or something. I had to watch some ~2013 convention appearances to see that was not the case. I think he was basically trolling Shatner. And I do think I understand why.I think anyone who's seen The Captains can have no doubt of this. Brooks comes across as intense and... unusual. Not in any particularly unpleasant way, but I can see how it might be difficult to be around for long periods, especially if you're just not on his wavelength. The whole sequence where Brooks will only answer questions by playing piano chords seems to leave even William Shatner genuinely lost for words.
I think Brooks is part of the group of people who never really "got" Star Trek, except he is unique in being an actor drafted into the lead show of one. Star Trek can be silly, and even on DS9, many moments of dramatic tension were solved with technobabble, that was followed by people pressing buttons or wiring a piece of technology. The actors who got most into Trek were ones that didn't take themselves too seriously, and ones who loved (or came to love) science fiction and the possibilities it opened. I think Jonathan Frakes is a good example of that.
Never Avery Brooks though. His favorite episodes were all the most dramatic ones involving racial issues or characters, rather than a scenario. Science fiction provided the conduit to explore it, and then old fashioned acting did the rest. And that's fine! But it's also like 5% of DS9. Because he was a pro he delivered every line about the Dominion and Dukat with intensity, but did he ever care about the story? I doubt it. It's fantasy and I don't think he does fantasy in that respect. Which is why when it was over for him in 1999, it was truly over. No inkling to revist the world. No inling to even talk about it either. He had no attachment to stories about people pressing buttons to solve weird stuff in space.
So he hasn't gone to a convention in years. He almost never grants interviews about DS9, figuring he said all there is to say. He wouldn't even give a few hours of an afternoon for the definitive DS9 Documentary (though he supported it) to just say some things, even if they had been a repeat of it before. I also do wonder if Cryptic even bothered to approach him for Star Trek Online, given they've gotten everyone else from DS9 except Brooks, Meany and deBoer.
And then he does that Shatner interview, and starts acting strange. I absolutely think it's a "my house, my show" moment. He's spent 15 years talking Trek in other people's rooms, on other people's terms... and then and there he gets to do what he wants with it, and he just goes.
I don't think it makes him a bad guy, or even disrespectful. The massive fandom and extracurricular legacy of Trek isn't for everyone and over the next 40 years you'll probably be able to count the number of convention appearances Chris Pine ever makes on one hand. Brooks is hooked into it inextricably at this point. I don't think he resents it. But I also think he doesn't particularly care for it. It's not part of his everyday life, like it say, some of the TNG actors who tweet something Star Trek adjacent every day.
As it is, I think having the aloof Mr. Brooks is a small price to pay for getting the legendary, irreplaceable, Captain Sisko.