First off, my goal was to address "What should I do if they don't tech?" with the answer being: build meter and go for an airthrow, because it forces them to do something or take damage.
Now then, Iso - it is a gimmick, but it's better than you and Mac indicate. If you're getting hit when you try it, you're doing the D too early. Haku j.C and Jin j.C will both hit Tager if he D's right away (although you can j.C clash instead).
The point of the mixup, though, is that you can hit D at the last possible moment, and confirm the 720 if the opponent pressed any button or did nothing. You don't actually need much pull - D is very strong vs air. Your goal is to have them land into the edge of the 720 range, so that a falling normal will whiff through Tager's head before the superflash. In fact, even without any sleep, you'll notice I press D very late, and have recovered by the time a Haku j.C would have been in range.
If, instead, you notice they altered their momentum in some way, it's easy to turn the 720 into a Collider...which at that point is fairly free since they stuck themselves in the air.
Axis - get on that, I expect to see Mac posting that you landed this despite his j.C by next week. (^.^)
Gimmicks get better the more you understand them.