"Damning with faint praise" is a pretty subtle English idiom. In my experience, it's only used to refer to an instance where someone is socially obligated to offer praise, e.g. a doctoral adviser writing a reference for their student, who gives such faint praise that they intend the recipient to infer that, were they allowed to, they would have been explicitly critical. Since the comment author in question was under no such obligation, I don't think the idiom applies.