Chances are, the commenter probably is just plain stupid and simply has no idea what he's talking about.

That being said, there is an academic current that believe that the influence of Lockean liberal philosophy has been overestimated and that America owes much more to Greece and Rome (and much less to Locke) than the mainstream admit. The mainstream view is what is known as the 'liberal tradition', whereas this smaller current is what is known as the 'republican tradition'.

Nevertheless, even those of the 'republican tradition' do not really posit a 'Greco-Roman liberalism', only a 'Greco-Roman republicanism' or 'Greco-Roman democracy'. But liberal ideology and democratic political systems were considered quite distinct until the 20th century, at which point they essentially completed a process of becoming fused together. Hence why we have liberals who tend towards belief in absolute monarchism, like Hobbes. And liberals who clearly saw some peoples as savage and others not, and believe that imperialism by the latter is good for the former, like Mill, who was also an ardent feminist and late in life also something of a socialist. I think these men would be shocked at the kind of systems of today, where it seems like we are living under an anarchic mob rule at one time (like America with the BLM madness in 2020), and at others like the whole system is simply a sort of front for some true power working from behind the scenes (as with the whole response to Covid).