Don't know about his linguistic work. As much as I can gather, even if not 100% correct he was hugely influential in linguistics. This is a how (good) science usually works. Someone postulates a theory which tries to explain a thing, and is then proven and/or disproven. If well done it stays important even if disproven.

However his politics? It's a barely coherent mess with only one basic postulate - "America bad". Anything that US does is automatically bad. Anything that any enemy of US does is automatically good. Turns out to be correct sometimes but there is no true moral and philosophical underpinning to it. He build his political career on the "even a broken clock is right twice a day" principle.