I'm confused. Is tamping anything to do with the pressure needed to push water through coffee? To me tamping is the pressure needed to compact the grind enough to slow the hot water long enough to allow prop[er extraction of all the components of the bean.
Also, and please forgive a newbie for what might be a dumb question, is 9 bar the pressure needed? I thought it was less than that for good espresso extraction.
Even with that aside, the average group filter is a lot larger than 1 inch2 - at somewhere closer to 2 across the area is 6.28 inch2 so wouldn't htat change considerably the pressure applied and the travel for the lever? 130psi sounds like a hell of a force to be applying to coffee... Do it in a plunger and you'd be picking shards out of people across the room.