To answer your first question, yes.
As to your second question, maybe you should ask yourself that question. I'm the one providing proof, conceding where there is reason to concede, you're the one making excuses and changing goal posts.
Now back to what was being discussed. Again, I feel like you don't even know the mechanics, Mustang does not work the way you think it does in the air.
As for the recovery of a knockback, what combo video of a stylish player is showing off their ability to take hits and knock back, its a useless skill, because once you're good enough you're usually not getting hit in a DMC game combo video. I thought you were reasonable but I'm starting to think otherwise.
Also, I am playing DMC4 right now, those videos are from me, so trust me I know its hard as hell to stay in the in the air DMC4. That's not what is being discussed here. We're discussing the overall value of skills and their approximate equivalents in DmC. However, assuming you're right, the purpose of that skill is staying in the air in DMC4, and since staying in the air is not an issue in DmC, that skill is admittedly useless and not in the game.