You're headed in the right direction, but your characterization isn't accurate. Strictly speaking, Socrates wasn't trolling the sophists so much as drawing attention to their manipulative practices. The sophists weren't infamous for employing rhetoric, but rather sophistry and eristic. Here, rhetoric is to sophistry what polemic is to eristic.
Where rhetoric is an art that emphasizes logical, sound, effective and clear communication for the purpose of persuading someone of a position that the rhetor believes to be true, the sophist employs fallacies, flattery and other methods of appeal to manipulate someone into accepting a position, regardless of the truth of that position, for other ends. The highest value for the sophist was oratory excellence and skillful use of language, not the attainment of truth. Analogously, the polemicist aims to dispute a position, but he does so while maintaining the same ethos as the rhetor, i.e., by attacking what he deems to be false for the sake of the truth. The eristic, on the other hand, shares the ethos of the sophist, i.e., he is unconcerned with the truth and aims only dispute for some other end. Josef Pieper's puts it well in his essay "Abuse of Language, Abuse of Power" when he says that when language is disconnected from truth, it becomes an instrument of power.
Both rhetoric and polemic are useful during intellectual exchanges. Indeed, the most successful philosophical arguments often consist of disputation of a previously stated position, followed by argumentation in favor of another position and here both rhetoric and polemic may be used.
I was rather annoyed by what appears to be the author's ignorance of these ancient arts.