The point is the almost nobody thinks of the classics in racialised terms. Those white supremacists which the author is talking about are notably absent from the public discourse [1], they seem to be an incredibly rare species which gets an inordinate amount of attention given their rarity. That means that this author and others like him are the ones who are attempting to racialise the classics in the public discourse even if they claim to bring race into the discussion "to keep others from doing so" [2]. For most people the Romans are either the opponents of Asterix, something related to Julius Caesar or the predecessor to the Roman Catholic church.

So, yes, this is the motte from which he launches his missives.

[1] Do mind that white supremacist is a term which has an actual meaning, it is not just a label which can be stuck to people who you happen to disagree with. Richard Spencer is a white supremacist, Donald Trump is not a white supremacist - even if you do not agree with him.

[2] This is a well-worn tactic, used by "anti-racists" like Ibram Henry Rogers (who calls himself "Ibram X Kendi") who profess racism in order to fight racism, by groups like Antifa who look and act like blackshirts while claiming to be anti-fascists and by other activists.