The vatican got some grief for not criticising Hitler and hence making it easier to do holocausts and the like. Maybe they feel they should avoid that sort of thing?
Pope did some little Hitler criticising, just not enough and Vatican kept neutrality. Meanwhile catholic priest Tiso became a president and literally presided over killing of Slovak Jews and their persecution.
Today you have catholic priests openly promoting semi fascist politicians and parties. Pope is taking side in that too.
You dont see people who want pope to be super neutral take issue with these. You dont see them take issue with Vance using his catholicism to tie his policies to catholicism.
What US is doing now is not an abtract politics eith no tie to religion - they claim to speak for European christianity. If pope stay silent, it will ve taken as confirmation.