Firstly, the flaw in your strategy is that right after Tsunade or Sakura jump into the air and disrupt the jinton, Mu can go invisible and fly after them back on their descent to the ground and brain them with a sword through the head while they are in midair, unable to dodge. An explosive kunai tag is doing nothing to Mu considering Nagato tanked dozens of them which were directly stuck to his legs and Sakura tanked one at point-blank range (also keep in mind Mu's reflexes allow him to see the kunai coming and escape the blast radius altogether.)
And yep, Tsunade and Sakura have no counter to Mu going invisible and splitting up then stabbing them with a sword. protecting their neck area doesn't prevent them from getting impaled by a sword through the brain.. Lol, Tsunade being able to hear a heartbeat doesn't necessarily mean she will be able to locate Mu's exact position and strike him with a punch which would be easily dodged anyway. She has to be completely focused on listening, and for all we know, she can confuse it with the sound of her own heartbeat, or Sakura's heartbeat. Then you have to factor in the sounds of the battle, like rocks crumbling, slugs splitting, Sakura talking, If Sakura and Tsunade aren't within close proximity of each other, then Mu can just go after Sakura first.
Mu can also trick his opponents - have Mu split bodies and go invisible, then make one body go visible and act as a decoy - while their concentration is momentarily focused on that body, the other Mu (invisible one) can stab either one through the head and kill them. (Or Mu can purposely let one of his bodies be killed while leaving the other one invisible - and once the girls drop their guard thinking they've won, they get surprise decapitated.) Mu can further confuse them by visibly splitting bodies and making one go invisible - and since intel is full they know Mu can't use jinton in a divided state. Well, the bodies can merge back together (the invisible one merges with the visible one) and then Mu catches them off guard with a jinton they expected him not capable of using.
What's more Mu can go invisible and hide behind any of these
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, where he can load up the jinton and atomize either Tsunade or Sakura from behind the rock. Because he is an acute sensor, he can still locate them and track their movements from behind the shelter of the rock, and therefore know where to aim his jinton. Inb4 they summon katsuyu who splits up and keeps a lookout from all directions then notifies the girls when Mu becomes visible; this is a good method in theory, but in actuality it takes a little bit of time for them to summon the slug, instruct her to split, have her crawl in every direction, then notify the girls when Mu becomes visible, then Sakura and Tsunade have to react. Mu can hide behind a rock and fire off a jinton at Tsunade in that time, and if either Byakogou user is killed then the other stands no chance.