I have done that too.
It makes the console shifter dangerous.
I've had one foot on the ground and realized the truck wasn't in park because it was starting to move. (Was only going to be out for a short time, so wasn't shutting it off)
Park has always been the shift point after park on every other automatic that uses a shift lever.
Like you said, push the button and move the lever to the end - past reverse.
We also have an Acadia, with the button shifter.
Didn't like it a first, but it's a way better that a console shifter. Kinda thought that's what the LD's would get when they went away from the column shift.