misd-agin: Yes - moot point - however "old hands" on the A320 will tell you that this type has a history of this. Parking in done via a different HYD system (depends on vintage) When initially moving off after pushback the brakes are checked for two reasons a) to check that the normal brake system has taken over and b) to check that the parking system pressure has dropped to zero and that the aircraft moves smoothly.
ALL I was trying to say was that setting the parking brake on the runway will introduce another variable into the equation which MIGHT JUST MIGHT go wrong. I was not starting an arguement about procedures or SOP`s.