Shatter cohesion isn't as hard as you state - it's not that a single condition needs to apply to every unit, but rather that every unit needs to have one of these conditions. So if you're going second, and at the end of last opponent's round they have three units sitting on three objectives - if you can get all of them below half-strength, you score Shatter cohesion, as they're half strength and everyone else is more than 3" away from all objective markers. And also this provides a solution to some dilemmas of "stand on objective and die, or abandon objective and lose on primary" - now it becomes reasonable to set up situations where you maximize doing damage at the cost of not holding objectives and aim to score just 20 in the first 3 turns while shooting enemy units on objectives (with e.g. immortals) since you can then score this secret mission.
I believe you would still lose if your opponent chose the secret mission where are you don’t have any battleline on the board if you’re playing hyper crypt, and you put them in reserve. I think this counts as not having any battleline units on the board. I don’t have the mission deck in front of me so I can’t check the wording …
