This rule absolutely works in Germany. In the US i would argue it also applies to an extent. Anywhere else it just means "nationalist" instead of "racist" which is only slightly better. States arent something to be proud of. Your state apparatus doesnt care about you and never will. Lots of people see their country's flag as a cultural symbol, but thats just misguided imo. Legally speaking the flag is a state symbol, not a cultural symbol. Flying a state flag means endorsing that state. This becomes apparent when a state turns bad like Israel. If you fly an Israeli flag people will assume that you endorse Israels genocide. Doesnt matter if there are a bunch of people living in Israel that dont endorse the genocide, the flag is the state and the state is the flag.