What do physicists think of Roger Schlafly?

Practically no physicists have ever heard of him. Which lets you know all you need to know right there: the guy has made no contributions that a physicist would have heard of.

If they'd bothered look look into him, they'd notice that he's everything you'd expect from a contributor to Conservapedia: he has a foreordained conclusion about things and sets about torturing what evidence he can cherry-pick until it yields that result. They'd be disappointed to note that you can have a PhD, even in a technical field like mathematics, and still be an idiot.