I don't need to know the internal - it's pretty obvious. When you are test launching a rocket, MaxQ is the moment to test (aside from ignition, which you can te

I don't need to know the internal - it's pretty obvious. When you are test launching a rocket, MaxQ is the moment to test (aside from ignition, which you can test with static fire, so not really "test launching a rocket"). So SpaceX wants to test the booster launch; they have tested everything else on the ground that they realistically can at this point. That means ignition, get off the pad, MaxQ. Everything after that point is gravy. Of course there are plenty of systems after maxq they want to test, but not to sound like a software project manager, but "is the juice worth the squeeze?" Everything past maxq may not happen if the rocket goes RUD before or at that point, so how many points do you really want to be putting into stage separation, boostback, reentry, when those engineers could be triple checking Stage 0, fueling, start sequence, and liftoff? Was it supposed to tumble and explode? Of course not. How many weeks of delay of booster launch is "don't tumble during stage separation" worth? SpaceX says on the order of zero, save it for the next unit in the heckin rocket assembly line (that is wild to say out loud but that's what it is).