Even if he was targeting different ethnicities just because of the risk they could’ve been spies, what he effectively did was put a different “value” on his citizens, which is the opposite of social equality, a center aspect of leftism.
Maybe in his and his followers’ minds the end justified the means and he was actually aiming to build a better society for everyone, but ultimately what he did was enact racism and social hierarchies. If that still counts as left-wing to you we have different definitions.