I think I would disagree about that. First of all, rebelling is definitely NOT easy on jailbreak, the warden can easily take care of rebellers due to their crits such as rockets or stickybombs which makes it extremely difficult to find an opening to be able to run away/rebel. Then there is also the fact of bunny hopping which means that any guard can just immediately catch up to the rebeller and kill him. Second of all, scouts double jumping wouldn't even be that overpowered on minigames, because it can easily be restricted by the warden, and also that there are not many minigames where double jump would even be useful in the first place. And you say that picking any other class for minigames would be stupid, but there are classes such as soldier with conch and medic and sniper with cozy camper who have self healing, which I would say outshines double jumping by a lot. Then there is also the fact that scout is not a very powerful class in Friendly fire situations such as cellwars, meatgrinder and hunger games.
Lastly, I do not see how pyro's airblast can be abusable, if you mean airblasting non-rebelling reds, than that would just be classified as a freehit and would hopefully be taken care of by a donor/admin/moderator. Which also raises the question, if knockback on blue team is so bad, then why are other knockback thing allowed? Such as shorts stop, loose cannon and a few others. In conclusion, remove warden crits, leave x1.5 damage for blues, enable double jumping for BOTH teams, and enable pyro's airblast.