The way I heard it was that the Viet Cong thugs were being supported by the Buddhists, so sure - he may have dealt harshly with their support group. He wasn't trying to impose Catholicism, he was trying to survive.
And yes, JFK should never have allowed the 'hit'. Never the great leader of 'Camelot' that the Media created.
A friend of mine showed me a news report of a Vietcong propaganda film that featured the leaders of the Vietcong and 4 American advisors they captured in 1963. They showed the leaders of the Vietcong, all with names I can't spell or pronounce. One was a member of some sect, the other a Buddhist, the other WAS a Roman Catholic.
I heard the same thing that Buddhists were helping the Vietcong but I have a hard time equating that since the reds were atheists and since Buddhists were being slaughtered by Mao especially in Tibet.
Why would a plurality of Buddhists support the Communists?