"Take a breath" is a colloquialism based upon the common human habit of an  excited person speaking in a rush without taking time to catch a breath.  It has the same meaning as "calm down", and is therefore dismissive of the level of excitement that the other person is expressing, or that you are implying the other person is expressing.  In this context, it was clearly a denigrating statement.   As to your inference that Tom Davis  was putting forth a "blanket indictment of politics/politicians as something inherently bad":  I can't see that in what he wrote.   I read him as pointing out that Bailey isn't being straightforward about the political nature of the rally.   You actually seem to agree that it is a political event, and your inference does not seem justified by what is written.  Perhaps you know Tom Davis and that conditions your reading of his words, as I know Bailey Stover (as do many readers here)?  My "problem" is:  Your (now admitted) lack of interest in civility.