While there are certainly well-made classic movies I find unappealing...The Graduate...I don't believe I've ever attempted to scold anyone else for enjoying them. I've certainly never advocated a movie be banned or censored. The idea of criminalizing a piece of art or entertainment, if only in peoples' minds, is one I find totally repellent.
Aside from seeing the Jaws trailer on a large screen in a movie theater...when I was five...I don't recall any Horror movie giving me nightmares. Certainly not panic attacks, nor PTSD.
It’s possible Kubrick placed the bear imagery in the film because it matches the story's theme of fathers murdering their wives and children. Adult male bears are known to kill bear cubs which are not their own and sometimes kill the cubs' mother in the process.