the problem here is that "support" has a floating and ambiguous meaning.
there's "support" in the sense that, should he kill Hitler, that would be a positive surprise - but I have no involvement with the matter. I "critically support" the killing in the same way I critically support better weather tomorrow. That is to say, I like it, but do nothing to impact it. In this case, the "support" is purely verbal. (and as such, isn't really support at all most of the time. Indeed, for communists to go "great work Mr. Von Stauffenberg!" would almost certainly be a practical attack
on his position.)
then there's support in the sense that we actually provide some support, perhaps by taking some action to delay Hitler's movement, at which point we're now actually materially impacting things.
Results matter more than intentions, but the western left exists practically only as a coalition of good intentions. A minor communist party will declare that it supports Russa against NATO imperialism or supports Ukraine against NATO imperialism, when the reality is the only thing it's actually supporting is the sound of its own voice - everyone could swap sides and Zelenskyy and Putin would sleep just as comfortably in their beds that evening as they had the evening prior.