You don't have to be a leftist revolutionary to play this module, but it helps!
Seriously, the module as-written requires your characters, at the very least, to buy into the idea that violent revolution can be a good way to create lasting change. (I happen to grudgingly agree, but you might not. Then again, if you don't, why are you even looking at this module?) That isn't to say you won't get any use out of it if you don't want to play a revolutionary, though: Mabel Harper has created new fan characters, factions, and scenarios that can work for most any group. I plan to use the Knives (an orphan gang) and the Pink Roses ("a gang of gun-toting sex workers who know how to use 'em") at my own table. Worth the investment!