Chomsky isn't just wrong. People can be wrong AND well-intentioned. Chomsky pushes an active political agenda and will cling to it regardless of the facts.

Venezuela is currently collapsing because it based its entire economy around a consistent rise in the price of oil. No one disputes that, it's simple fact. But bad management in a socialist country doesn't fix Chomsky's worldview, so he blames the collapse of Venezuela on the United States. Brazil is experiencing a massive corruption scandal, as /u/vibrunazo points out. Virtually NO ONE believes these people. But corruption in the party is against Chomsky's worldview, so he makes it into a massive conspiracy.

It wasn't an ad hominem. It's a statement of fact that Chomsky has no respect for truth or academic rigoiur in politics. He's a polemic, pushing his own political worldview, evidence be damned. This is a guy who actively denied the atrocities of the Khmer Rouge and as far as I can tell, has never recanted. That's up there with Holocaust, Holodomer and other genocide denials—and usually those aren't coming from people considered as academics.