As far as I know, only the Nazis used a black swastika in a white circle on a red background.
I'm aware of that, but he could claim that it is also used in some areas of Hinduism. However, that is definitely besides the point. Even if you believe the claims made by Holocaust-deniers, there is still no denying the political violence openly carried out by the Nazis, their policy of invading other nations with the only justification of wanting "living space", the fact that Nazi Germany was directly responsible for starting the Second World War, and the sheer number of civilians in occupied territories who were killed in actions not a part of the "Final Solution" (all of which the Nazis themselves fully admitted). The use of the Nazi Swastika is questionable to say the least, illegal in several nations, and frankly something I find disgusting.