Okay, you still aren't paying attention to the mechanics of how the "failure" is actually happening. It is the slow closing of the slide that allows the back plate enough time to drop when the free traveling striker impacts the striker block and pushes the whole striker assembly forward. If the slide closes at a normal rate there isn't enough time for the back plate to drop out of lock before the slide closes fully, preventing any travel by the back plate before the striker assembly can rebound and relock it.
Again, everyone with a P-10C can confirm this. Even if you set up the failure with the rotated striker stuck on the frame and holding the slide open, you can't move the back plate. This is because the striker assembly is fully to the rear and partially embedded in the back plate. Only when you rotate the striker back to it's normal position, allowing it to jump forward, does the back plate momentarily unlock. In order for the back plate to displace, the slide must also at the same time be prevented from closing. If the slide is closing at normal velocity, the stuck striker impacting the frame realigns the striker, but the striker assembly can't travel forward fast enough to impact the striker block with enough force to unlock the back plate because the slide is still traveling forward too.
So, again, this "fatal design flaw" is BS. Now, may some guns have issues? Sure. There may be some parts not to spec in some guns that need factory replacements. Every gun manufacturer has that issue. Is this particular "failure" endemic to the P-10C design as a whole? Nope. It's not even an issue at all once you honestly understand what is being done in the original video (Seriously, do you still not see his left hand slow closing the slide?), how the failure is induced, and how it effects the gun in the real world.