I just thought of something. What the post hitstun 2 frames of throw invincibility means, is that:
After EXGH, when your +1. You can’t connect U1 until 2 frames later. After 1 frame later when your opponent comes out of frame disadvantage, you still have to wait 1 more frame until you can land U1. But you could activate U1, since it has 2 active frames, whiff 1 active frame and grab them ASAP when they become throw-able again on the very next frame. Now that would mean, they can jump your U1 post Ultra Flash, during that whiff 1 frame, as expected.
Now, what happens if your opponent has a 1 frame grab Ultra like Zangief, T.Hawk, or Hakan. Would that mean, that in that scenario, they can grab you 100% of the time even though they’re at frame disadvantage, if you don’t jump or backdash? So basically, if you turn on your U1, they grab you with their U1? Maybe even on-reaction post Ultra flash?