I think a lot of ex JW activists may use that term simply with reference to the idea that they actively support work against the Watchtower organization.
The Miriam Webster dictionary states
: one who advocates or practices activism : a person who uses or supports strong actions (such as public protests) in support of or opposition to one side of a controversial issue
Lloyd coined the phrase "aggressive activism" and included public protests in this term. He did this to distinguish his type of activism as being acceptable as opposed to actions of other JWs as being unacceptable. However, what he is doing as opposed to other activists fall under the same definition.
He's simply changed the dictionary term of 'strong' to 'aggressive'
It's not activism that most ex JWs provide, it's support, encouragement and exposure.
But where do you draw the line of whether an ex JW is an activist or not?
For instance, I gather Simon wouldn't consider himself an activist and I doubt Raymond Franz would.