Being unhappy, or even outraged, by the new Pope's stand on the issues is one thing
Holding him accountable for actions he took at the age of fourteen under a dictatorship is quite another.
Most liberals would be outraged if, for example, we attacked the Pope for being a former member of the communist party, even though the communists killed as many, or more, than the Nazis.
There's plenty of fodder for the left, or even moderates, to attack the new Pope on. They don't need to resort to 50 or 60 year old stuff.