When I think of the settlement of the Pale, and the antisemitic Black One hundreds who participated in numerous pogroms I think of the Cossacks. They were the enforcers of the Romanov policy of discrimination and death against the Jews in the Empire. This is great that these two former bitter enemies are joining forces. It tells you volumes about the geopolitical conditions of the world that would bring these two disparate groups together.
I agree with you. I love it.
You mention the enimosity from days long gone. Although your historical connotation is fundamentally correct and relevant, I think both the Cossacks (or: a good number of them, anyhow) and the Jews have found a common enemy in today's islamism.
And that would be a good thing indeed.
You could go a bit further back in history, say, to Khmelnytsky and his cossacks.