Well, the thing is, when you parry something, the screen actually freezes a bit and you get a small frame advantage where you can perform an input before whatever the opponent does. It’s like an exclusive time segment where only you can act. Now, according to karathrow.com, Hyper Bomb has a 3-frame start-up, and we all know that you can jump out of it after the super freeze. So it appears that jumping out of a grab requires 3 or less frames. I don’t know exactly how much frame advantage parrying gives you, but let’s be minimal and say it’s 1. We know from Hyper Bomb that it takes at most 3 frames to jump out of a throw. So say you parry something and immediately hold up, and then bam, next thing you know the screen freezes and you see Akuma do the demon. Well, you’ve already spent 1 frame jumping. Demon has a 2-frame start-up before it goes into the actually grabbing frames. By the second frame of the start-up, you should’ve jumped off the ground already.
This is all very confusing so let me use the below chart. T: A denotes that Action A happens at time T measured in frames, so something like 3: fireball would indicate doing a fireball 3 frames past time 0. Note I’m not counting the time a super freeze takes up.
Case Alex vs Ryu:
0: Alex performs Hyper Bomb. Screen freezes. Ryu holds up during super freeze.
1~3: Hyper Bomb start-up frames. Ryu jumps out at some point. Let’s say at 3.
4: Hyper Bomb whiffs.
Case Akuma vs Ryu:
0: Ryu parries an attack.
1: Ryu gets this frame exclusively due to the parry. He holds up. (note I’m assuming that parry advantage is 1 frame)
2: Akuma performs the demon. Screen freezes.
3~4: Demon start-up frames. If it takes 3 frames to jump, Ryu would’ve jumped at 4.
5~: Demon whiffs.
Hope I made that clear. =) So yeah, because of this I believe that it is technically possible to jump out of the demon after a parry. Although, nobody ever, ever holds up after a parry any way, so doing a demon on someone parrying at point blank is almost guaranteed to connect.