Wow, had to check this one was real, and jokes on me it's still up on his Twitter, complete with him stubbornly defending himself against everyone telling him he's nuts. How did the Dilbert guy lose his mind so completely?
I would like to direct your attention to the Behind the Bastards podcast episode entitled "Part One: How The Dilbert Guy Lost His Mind" from July 11th, 2023.
He's always been a little like this but pretty quiet and subtle about it. However once he started losing his ability to speak he lost a lot of social interaction and kinda went nuts.
It absolutely is worth a listen though (as is the rest of the podcast).
He lost his voice starting in like 2005 or 2006, then got surgery to fix it in 2008. Real Time was running starting in '03, but that was way before Trump was politically relevant so I'm betting you saw him after he'd lost his voice, alienated everyone in his life and gone nutty, then gotten it back.