He is extremely well-known around the world and is far from alone. He is one of many scientists working on this stuff.
If he were even remotely "crazy," Stanford Medical School would withdraw his tenure so fast it would make his head spin round (I am sure they have considered that option).
College professors are an interesting lot. One of my professors was probably the most well-known in the study of UFO abductions. IIRC, he worked on his research with a professor in California, though probably not this Stanford professor who is much younger.