Today’s pope is “liberal” only in the context of Catholicism. Compared to other recent popes he’s a liberal. In context to the wider world outside Catholicism, even today’s pope isn’t considered liberal by a long-shot.
In fact, even the the two previous popes before the current one, who are considered to be very conservative by all accounts, were economically liberal, opposed the death penalty, supported open borders/free immigration and supported generous welfare. So could you really even consider Pope Benedict or Pope John Paul II to be conservative, given those positions?
In any event, in today’s America those affiliated with the left and who call or consider themselves to be liberal or “progressive”, take social positions that are completely anathema to Torah and Judaism, even in the context of what is permitted/prohibiited for Bnei Noach based on the Sheva Mitzvos. And as such, in the context of the American political scene, it is certainly prohibited to be or be affiliated with the liberals, left, progressives and Democrats given their support for toeiva, abortion, right to suicide, right to pull the plug on the terminally ill, and generally supporting public immorality.