Chomsky is an expert, in quite a lot of ways. He is THE universal grammar guy. There's just a lot of recent scholarship that likes to dispute him. But that's how science works. It's important to keep citing people who came up with influential ideas, even if research later goes in other directions. In my field, for example, everyone will probably always keep citing B.F. Skinner, even though it's pretty universally agreed that a lot of his conclusions were super off-base. Doesn't mean he didn't do a lot to move the field forward. Chomsky is still far more relevant than Skinner.
Now, I don't extend the same sentiments to people like Freud. Did he write a lot? Yeah. Was he super influential in his field? And how. But none of Freud's work was empirical - it was all just him making stuff up that sounded good, and research in years since has pretty much debunked it all. I probably wouldn't put much stock in anyone who appealed to Freud as an expert. But I don't feel that Chomsky is in the same category at all.