That social media woman had the best explanation. He heard from some aide that Venezuela and some Central American countries were pouring out their mental hospitals, jails, and insane asylums to cross Mexico into the U.S. And on another occasion, he hears many are coming here seeking 'asylum.' He conflates the two definitions, and asks for a high profile example of somebody dangerous from an asylum., and Hannibal Lecter pops up on the first page. Without any understanding of political/religious/humanitarian asylum, he just runs with the talking point that everybody kinda nods their head to like, "Yeah, I think I remember that guy."
The other weird thing, besides him constantly pointing out one person to be cannibalized at each really, is he prefaces it with "The Late, Great Hannibal Lecter." Hannibal doesn't die in the movie. We know this because we don't see him die, but fade into the crowd in the Bahamas. And he resurfaces stateside ten years later for another rampage. Anthony Hopkins, as you point out, is still alive in real life as well.
First thing they tell you when you're showing dementia/early cognitive decline is to get out of your mental routine. Don't keep talking to the same people about the same thing over and over and over again. Just because you keep saying weird shit and it feels comforting, doesn't mean it doesn't accelerate the decline. You've got to expose yourself to new books, new groups of people, new activities requiring some brain power (puzzles, swimming, gardening, etc.), new shows and movies, new topics of conversation. It was one thing in 2016 when he was barely 70 because it got his crowd riled up because they craved easily digestible politics. But now, he's just running a paint-by-numbers thing, gets no pushback, and it's blatantly obvious to even the casual independent that he has no original thoughts anymore.
He's just on a loop to the bottom.