This is not a fair and accurate phrasing of the problem. Triggers have a breakpoint in the pull at which you expect them to fire. Discharging by touching the slide, even while the trigger is depressed, is not expected or acceptable.
This is not unique to the P320, Sig, or even striker-fired handguns in general. This could just as easily apply to a CZ-75B. There is no magic that keeps the striker from dropping until the shooter has their heart set on discharging a round.
There is a reason that rule #3 of firearm safety is to not put your finger on the trigger until you're ready to shoot
But there's nuance here.
They showed that with <=1mm of trigger pull (far less than the distance of the firing sequence), the weapon can be put into a state where miniscule input on the slide (consistent with typical holster carry) causes a discharge.
I'm not a firearms expert, but I very much doubt that any hammer-fired (and indeed, even the vast majority of striker-fired) weapons can be put into such a state.
Are you aware of any demonstration that shows another modern handgun being put into a state where this same amount of input on the slide can cause an actual discharge, let alone with <=1mm input on the trigger?
Yes actually. see the video I linked above: https://youtu.be/r1KoSBcn2bY?feature=shared
I wonder: do you know if there's a hammer-fired pistol which can be put into a similar state?