It should come as no surprise that Joe Lieberman and Joe Scarborough are full of shit, although I was a bit surprised that someone like RFK, Jr. would fall victim to the anti-vaxxers.
Then I read his article on it. It's a mass of hyperbolic conclusions, with no evidence provided for any of the assertions that he makes. There are "truckloads" of studies supporting the evidence. How big of a truck? How many? You do know that a truck could be loaded with nothing, right? Also, there's a "staggering number of earlier studies that indicate a link between thimerosal...and autism". Don't say that the number is staggering, actually give a number. It could well be a staggering number because it's very low- after all, celebrities wouldn't make baseless assertions without actual evidence. That's why they're celebrities, because they cannot tell a lie.
He gives absolutely no scientific evidence, so I'm afraid: