I really like your deep take on Kubrick/King's MK-Ultra and other symbolic acts that occur in the Shining. But It may not be completely the whole picture.
There's another side to this, which is more "wendigo/windigo". Isolation in many months of deep cold and snow can
change your mind. It doesn't break you in November when everything dies and the north winds come in and start to freeze everything. But by February or March, the relentless winds and can cold break you. If you don't take the proper "mental" hygiene the isolation and the quiet come after you.
I do think Kubrick and King had some knowledge of this phenomenon. Here we call it "Kee-Way-Tin" the voice or spirit of the north wind. It freezes your blood when you walk into it. It's both a physical and mental torture. If you check out "Windigo Psychosis" papers it was or maybe still is considered a legitimate mental health illness.
It is more likely possession. It's hard to explain it to people who haven't experienced that long silence, ice and cold for a prolonged period, but when you do - The Shining becomes completely believable when you throw someone who doesn't know what to look for as a threat into that situation.
Not a movie - but a great recount of some of those same elements that happen in the north...