Engaged Buddhists definitely see activism as a part of their practice.
To me that point speaks of dropping one's attachment to specific outcomes. I may work toward preferred outcomes, but if things don't go the way I want I accept that and go on to something else.
It's kind of like seeing the universe as a democracy - all outcomes are result of a vote consisting of the actions or influences of all the stakeholders (ranging from other people to the laws of physics). My vote/action is only one of many that has a bearing on the outcome. If I get outvoted I accept it and move on. To me the symptom doesn't mean "don't vote" so much as it means "vote, then accept whatever the outcome is."
One more thought:
Action in favour of a preferred outcome can be judgement-free, while "activism" seems to have more to do with getting other people to behave the way you think they should. I do have issues with that, since I think that right and wrong are human illusions, and that "should" is the single most pernicious word in the English language. But that's just me. YMMV, and you get a vote in everything too.
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