[cazum]

It can't be circular reasoning because it's not an attempt at reasoning. It's an incredibly common English phrase that means "The argument is independently bad on it's own merit", not an attempt to show a logical incongruity. Others have already explained why the argument does not hold up, I don't need to repeat their work here.

And if we want to be pedantic, "especially the part where they claim that the source has a history of bad arguments" would make my "argument" an ad-hominem fallacy, or perhaps poisoning the well, but not circular reasoning. But again, as I said, the argument is bad independent of the people who made it.