Idk. I don’t think this particular phrase would even enter my mind as something to chant, and I am German. That’s not the first time he chanted that, I’m sure. It is taboo for sure, but it’s not in the cultural consciousness a lot, there’s more “popular” nazi slogans. You’d either have to search your brain for something specifically Hitler related or be very familiar with the old anthem (aka singing it a lot aka being a neonazi).
I do not agree that this is the “most” Hitler thing though. There are so much more famous things, hut they wouldn’t fit the situation though.