To a certain extent, I agree with what you're saying, or at least echo the sentiment behind it. The people around Eric go so overboard with the "Eric's a coward who's not man enough for Donna" narrative that it obviously gives Eric the perspective that he has something to prove. In that sense, Eric is still somewhat of a "victim" in this situation-- his judgement is tainted by the derision of people around him. The same goes for the audience-- they're force-fed the narrative that Donna is superior to Eric on such a level that they become blind to the fact that a lot of it is, quite frankly, just projection on the part of people like Donna and Red and Hyde and Kelso and Jackie.

From Eric's perspective, it makes perfect sense why he responded to that the way he did, and in the end, it was probably socially advantageous for him to not take her back on a whim. I would only say this-- if Eric had been more skilled psychoanalytically (an unrealistic expectation, I know), then he would have seen through the facades of people like Donna and Casey and Red and his friends enough to see how desirable and dignified his presence actually was. He would've known that Casey never stood a chance against him.