Hitler judged people based on their loyalty to their race and not on their religious beliefs.

Catholicism drastically increased in Germany under the Third Reich.

Now, they may be doing some verbal slight of hand. Because technically he did intern some people who were Catholics, obviously. But their Catholicism was incidental to their imprisonment. If they're trying this tactic, th best response is to ask the idiot pushing that to ask if the Church allows civil authorities to ever imprison Baptized Catholics (which of course it does.)