From this, I think there's an analogy to be made about his concern for politics. I agree with you that such an active individual wouldn't shy away from action with the potential to shape their world/experience/pleasure (he even advocated against passiveness), but perhaps what he rejected was the falling in the trap of the useless politics game....
Agreed.
Having dipped just a little into reading Aristotle, I would say that Epicurus was reacting against basing a philosophy on the polis rather than the individual. Aristotle, Plato, the Stoics and others determined that what was good for the polis was best for the individual, whereas Epicurus determined that the best life results from an understanding of nature and through the experience of the individual. Beginning with the polis tends to lead to duty ethics and state religion, both of which Epicurus reacted against.
Whether a particular individual chooses to be active in politics would be based on that individual’s analysis of their desires, not on a blanket proclamation that politics is to be avoided.