Bottom line
Even though JFK was Catholic, he recognized the persecution of the Buddhists was wrong.
JFK changed his position against the Deep State (CIA). He was already angry at the CIA and fired the director Dulles after the Bsy of Pigs fiasco. He made a statement the he would smash the CIA into a million pieces so events like this could never happen again.
JFK realized his mistakes and issued orders to withdraw troops from Vietnam. He was furious over the assassination of Diem and his brother.
The CIA needed Kennedy dead. And it happened just 20 days after Diem was assassinated on November 22, 1963.
Johnson escalated the was to please the CIA and win the 1964 election against Goldwater.
And another thing, you ARE aware that the whole “CIA being responsible for JFK’s assassination” was actually Soviet disinformation, right? Yeah, that was actually made as a result of a KGB disinformation campaign called Operation Dragon, which went into effect literally a DAY after JFK’s assassination. Ion Mihai Pacepa actually goes into full detail about that whole operation, which his boss had some involvement in, as did him to a certain degree. Just read up on his book “Disinformation”. He goes into full detail about that bit, and various other KGB disinformation campaigns (and he’d know, he also played a role in Operation Ares [which was the disinformation campaign relating to the anti-war movement regarding the Vietnam War] and Operation Che [you don’t need two guesses as to what, or rather, who that referred to].).
Besides, why would the CIA want JFK dead for withdrawing from Vietnam when both he and McCone (the boss of the CIA at the time) never approved of Diem’s assassination in the first place (well, approved as in signed off on it with full knowledge and a definite order, as Kennedy specifically stated he intended to make sure McNamara and Rusk were notified BEFORE the op was cleared, and even kicked himself over having approved it on a Saturday.).