He's essentially reiterating Mac's argument from It's Always Sunny, casting doubt on people who deliver information by informing us that "Science is a liar... sometimes".

It was also people who found out those people were wrong or lying.

Yes, Piltdown man was a fraud, but it was the same "scientific community" that discovered it was a fraud. Because there were things that didn't make sense even within the confines of the field of study.

That's the great thing about the process, it's ultimately self-correcting.