As someone who is stationed in the US military in Berlin for 5 years, I find the existence of monuments in Canada to the Waffen SS to be both shocking and unacceptable.

It's interesting to think about the fact that those monuments would be illegal in Germany, where school children learn about the Holocaust in great detail, with a focus on understanding that they — like all humans — have a responsibility to watch for signs that something similar may recur. To watch for signs so they can work together to stop it.

I'm thinking about Karl Popper's Paradox of Tolerance, where he notes that tolerance without limits (tolerating intolerance) leads inevitably to authoritarianism and repression. Popper, thinking of the Nazis, suggested that it's important to not tolerate some ideas and political behaviors.

Monuments honoring the SS, it seems to me, are among those things we should not tolerate, like (as you wrote) the Confederate flag.