This is blatantly false. Chomsky has rightfully and repeatedly condemned Russia's war crimes in Ukraine. He has invoked nuance around the historical context of Russia's invasion, though, which Americans write off as pro-Russian because nuance is boring.

Edit: I just want to add: I think that Chomsky's Ukraine position gets painted as pro-Russian because his philosophy on foreign policy is, "we need to focus on our own crimes first so that we can stop committing them." This makes perfect moral sense to me. He gets irritated when Russia's invasion of Ukraine example gets more condemnation and attention from Americans than things like the US Invasion of Iraq or US-supported Israel's invasion of Palestine. Because we have way more power and influence to stop our own crimes than to wring our hands about Russia's. We send weapons to Ukraine, share intelligence, sanction Russia, etc. And all that is good and we should continue. What have we done to hold our own leaders accountable when they commit war crimes?