If the signatories are a random bunch, then does the "APS Membership" graph above have any relevance?
Burt Rutan, the noted aerospace engineer, is no climatologist, but has written an analysis of the subject concentrating on how well climatologists have analyzed the evidence-- or rather, how poor their scientific procedure is. Just because he's not a climatologist doesn't mean he can't make valid observations about the field.
CAGW alarmists have tried to dismiss the analysis of Bjørn Lomborg, too, on the basis that he's an economist and not a climatologist. But his "Are We Doing the Right Thing?" analysis still makes valid and significant points.
However, if someone has been paid a salary or consulting fees by an "energy company" (i.e., Big Oil and their associates), then in most cases I think that's a legitimate reason to discount their opinion on the subject.
We are the 99%. A better world is possible.