But it's not the **only** and as Torquatus said it appears the later Epicureans (and I think Epicurus himself too) decided that for multiple reasons we cannot abandon the field of logic and philosophy itself to the pin-head Platonists. So if we are going to argue for pleasure on philosophic grounds, we have to have rigorous and bullet-proof logical statement of how all this fits together.
You keep using the word "logic" and I think we have to narrow down our terms. As I understand it, Epicurus's opposition was to Socratic-style dialectic, διαλεκτικός, defined by LSJ as "dialectic, discussion by question and answer, invented by Zeno of Elea, Arist.Fr.65; philosophical method." He didn't want to walk around, endlessly debating what things meant. He wanted to point to nature and declare, "There! Right there! **That** is what we mean (or should mean) when we say X." In that sense, I think he was "dogmatic" in the sense of taking a stand, planting his flag, and torpedoes be damned.
Now, he took those assertions and inferred larger points from them, but, as a starting point, he pointed to - what he saw as - the foundational meaning of words as phenomena existing in Nature and treated them as axioms as we might say. "An axiom is a proposition in mathematics and epistemology that is taken to be self-evident or is chosen as a starting point of a theory."
Later Epicureans got cold feet and got intimidated by other schools and their fancy arguments. I think Epicurus stood his ground as to the self-evident nature of his assertions on what was meant by pleasure, and the gods for that matter.
Were Emily Austin to say "I think Epicurus was right -- look at what babies do! - I rest my case" and close her book and sit down for the rest of the semester, she would likely be in very hot water, and probably not satisfied with herself either
That strikes me as a reductio ad absurdum. Epicurus didn't stop at his assertion, but used it as a foundation upon which to build.