It actually is circular as written, especially the part where they claim that the source has a history of bad arguments. As there's no evidence they evaluated the argument at all, we can assume this history is also based on reasoning of the form "it's bad just because" this this boils down to "it's bad just because, just like everything else they say".

Also, you're being too generous to assume there's an unstated justification for why it's is a bad argument. Pretty obvious that there isn't, they just assume anything said by the authors must be bad because tribes.