This assault, as I see it, is in that sweet spot at too crazy to work in real life but just crazy enough to work in an action movie. The odds are long enough that it would be a stretch for it to go off without a hitch, but I think they could reasonably accomplish some of their goals in exchange for some casualties, or else they could call it off without achieving their goals but preserve the gang's safety. None of the PCs are participating because none of them are really fighty-types. Brainer and Hocus are more interested in their mindgames, and the Operator is too busy trying to save her own skin and is kind of on the outs with the Hardholder anyway. The Hardholder could have gone, but I guess decided he'd be better off leading from the rear, as it were.
The ultimate goal is actually to break the blockade, but he is very explicitly going about that by trying to assassinate Elbow. So I figure splitting those into two separate goals means he either breaks the blockade but has a live, powerful enemy who can retaliate, or else he kills Elbow, but the military organization of the other gang is strong enough that they hold together and maintain the blockade even without their leader, or they accomplish both objectives but it'll cost them.
Part of my concern is that Jamaica is definitely more disposable than multiple other gang members--she's liked well enough, but none of the PCs actually care about her deeply enough to make killing her off that much of a consequence. The Hardholder will probably just promote someone else and move on, whereas the "significant casualties" option will have lasting repercussions. So since that's secretly a non-choice, I think I definitely want to fold those together. But then I need a fourth option... There were a few other things they mentioned as "it would be nice" type things, like also killing the second-in-command who's less sympathetic to them in the hopes that the more sympathetic officer would take over, or kidnapping a medic because the Brainer murdered the only one in the holding, but I don't think those would ever get selected since they're comparatively unimportant.