What mattered was the original description of him as "an economist at ..." which effectively neuters his very public positions on things like coordinated action w.r.t. climate change. He's absolutely entitled to his beliefs, but shouldn't be cited as if "oh wow, an ECONOMIST at SANTA CLARA says this, so ..."
But of course, this has nothing to do with the subject of the blog post, which is whether Cook paper asserting that "97% agree that humans are the primary cause of global warming" is at best a misleading application of statistics.
There is no need to have a particular background in climatology to understand whether the Cook paper was methodological sound, just a background in statistics. The argument Friedman advances is quite straight-forward, and you are welcome address the argument rather than try to disqualify him as a source.
I want him acknowledged as a source with a pre-determined axe to grind. He's smart, he's clever, he's sometimes right. But he's not J. Random "Economist from Somewhere University".
My point is stating that he was an economist at a respectable university was not to disguise his bias, but to emphasize that he wasn't just some random blogger, which was apparently a barrier for some people when it came to assessing his argument.