And I concur with your concerns, Cassius . From the sounds of it in these reviews, no one knows what the title was, and ΠΡΟC can mean both "to/towards" or "against (in a hostile sense)" but my understanding (rudimentary as it is) is that the latter meaning has the accusative case after it which is indeed ΤΟΥC (plural, accusative article: "the" [group of people]). And so Philodemus is writing a treatise "against" those people... Whether those people are fellow Epicureans or not, that's a scholarly question.
So, you're right to ask: Is the Tetrapharmakos a verse showing how it SHOULD be done or an example of a "watered down" version he disapproves of? My very basic beginner ancient Greek is nowhere near good enough to guess at an answer to that!!