Who is Garrett Graff? Watching a documentary and they keep referring back to him.

I’m watching season II of a UFO series on the History Channel (Disney Plus) - and overall it’s relatively well done for people who don’t follow the topic.

But they keep having this Garrett Graff guy speak and something about him is off. He seems extremely pompous and somewhat dismissive? Everyone else they have on this show are the typical talking heads.