Kosher Nazi references?

I'm somewhat puzzled about why some Nazi references are OK and others are right next to hate crimes.

What got me pondering was an article about the B'nai Brith in Canada making an issue of the Quebec student protesters using the Nazi salute to antagonize Quebec police.

B'nai Brith boss Frank Dimant claims the use of the Nazi salute, even in an obviously ironic or satirical context, "defiles the memory of the Holocaust and reminds us how quickly anti-semitism and the manifestations of hate can venture into our public discourse."

One of the problems I have with Mr. Dimant's take on this situation is that not so long ago Stephen Harper stood in the House of Commons and drew a comparison between the opposition NDP and the Nazis.

This was not problematic for B'nai Brith.

In the US any number of prominent commentators have compared Obama to Hitler.

This is not problematic for B'nai Brith.

And there's no politician anywhere in the world who is a bigger fan of Hitler analogies than Benjamin Netanyahu.

This is not problematic for B'nai Brith.

But when anti-capitalist protesters in Montreal mock the goonish Quebec cops with the Nazi salute, it's a problem?