If this is the Chris Kresser you are referring to - https://chriskresser.com/ - he is a lot more than just an acupuncturist.
Chris Kresser, M.S., L.Ac. - "M.S. L.Ac." means Master of Science, Licensed Acupuncturist. This is his formal training, all I'm saying is that he shouldn't be presented as an expert to Joe Rogan's audience in the topic he was interviewed on.