I don’t think the DO curse helped, but he still made the choices he made, even back from the moment he became the DO–like mass murdering the soldiers.
I agree that Rumple systematically made terrible decisions, I don’t think the point is to absolve him of responsibility. Rather, lets rephrase the issue. To what extent are dark and light magic qualitatively different, or are they like the Force in Star Wars, two sides of the same coin, colored by a person’s choices and motivations? Speculatively, and within the OUAT universe, do you think one could be a DO and “overcome” the curse by “lightening” the magic (rather than by breaking the curse through external means)?
Personally? I think you can overcome darkness. Rumple never wanted to. He needed that magic, the reputation, the abilities, of being the Dark One to find Bae.