I think, the startup delay is intentional. Otherwise they would tons of complaints by people, that notice 2 seconds after pressing the "GO"-button, that they forgot to put in another plate/cup/whatEv, opened the door, despite hearing the running water, and got doused.
My very dumb, 20 year old, dishwasher is perfectly capable of cutting the water when the latch is disengaged at any point in the cycle. I through utensils that got overlooked in up to 5 or so minutes after it starts and it has never caused a problem.
