It feels so weird to call this controversial. Doesn't that usually mean something similar to "polarising"? Who are on the poles here? Nazis, and the rest of the world?
From the wiki entry, "...interpreted by many as a Nazi or fascist" salute. It's like, yeah I guess it was interpreted by many that way, in the same way many people interpret water to be wet.
Why are the writers of this wiki entry giving so much wiggle room for Nazis? What the fuck?