Ooh--love this thread! OK, let me throw this out there: if we didn't know that All-Out War was coming up, would we be so quick to think it's a bad plan? I'm really trying to figure out if I would. As it is, we know that there will be a battle royale. If Rosasha knew that (if they're really gonna Thelma and Louise it, there needs to be a kiss in there somewhere!), I wonder if they would go forward with this. I think about our group's history with relying on others to help, and about what they've observed from The Kingdom and the Scavengers thus far: Morgan-whipped and quite possibly psychotic, respectively. Granted, Rick, Carl, Carol, and Daryl are the only original members left so they've had to trust others (and conversely) at some point. But Rosita's watched Jadis jerk them around ("Guns. More. Soon. Also. Hair. Awful.") and Sasha's watched Gregory be a total useless coward. I can imagine thinking, "OK, this is like herding cats. Screw it; I'm going rogue." I also thought it was a nice character moment for Rosita when she acquiesced to Sasha's request to take the shot: she didn't get it done, so leave it to the expert because Negan's death is the only thing that matters.

All that said--yeah, bad idea. As weallgotit pointed out, doesn't Rosita remember how Negan retaliates? Just as Eugene said: not by taking you out, but by taking out the people you care about.