I haven't actually tested this yet but can't you just sidestep cancel your PB and go for a ground attack if your opponent refuses to tech roll? Or does that not work?
IMO, if it were an unholdable from other strikes instead of a PB, it would be more useful as they're less reactable and your opponent may be afraid of you trying to FT him so he would be more likely to tech roll, while PB, as
@iHajinShinobi said, can't do anything against a grounded opponent. The opponent usually has at least 0.5 second to see what you'll do next after getting slammed onto a wall.
On paper, half of a second is enough for reacting to an opponent charging a PB due to its animation.
If you want to PB cancel and then go for a FT, it still can work, but only on those who intend not to tech roll and not to attempt a wake-up kick immediately..
Charging PB takes some time, and cancelling PB by SS takes 26 frames in-game, i,e, 0(20)5.
The fastest ground attack may be i12 2Ps, which actually hit an opponent at the 14th frame.
So in total, those actions may take more than 50 frames, which indicates that the opponent can attempt a wake-up kick as the skill info shows that most wall slams grant the attacker frame advantage only from 30 to 50 frames. This has something to do with the wall type and the recovery of the strike you use to slam your opponent onto a wall.
The fighting system has been set to let people who don't tech roll get less pressure from the attacker since DOA5U as it screws most of the FTs found in vanilla DOA5.
