Why would the tuso need to be more inline with the mosa though? you wouldn't take a mosa to a squid fight....you take a squid. squids are more rare, and a more difficult tame. and the mosa has a platform and a tek saddle.
So i did the math and comparing a squid to a mosa both with 40 wild points in health, the squid would now have only an approx 1500HP advantage over the mosa. But the mosa will now get more HP from tamed levels than the squid, so that advantage will quickly be lost. The mosa already had a significant advantage in Stamina, Food, Weight, Melee(tuso likely has better DPS, wiki lacks this info) and torpor over the tuso.
Now the only clear advantage the tuso has over the mosa is speed(well, and not being dismounted by jellyfish....) so this really seems to put them more out of balance than they were before. and comes with the unintended? side effect of making alpha runs and water cave runs even more difficult with a tuso.