Not sure I really understand why you'd want this in place at pre-order time - this service is intended for an AWU that has undergone some type of incident that may have compromised its waterproof integrity, such as physical damage, over-pressure or significant ageing, it's not meant to be a QC check on brand new watches.
In terms of diving watches, periodic pressure-testing is pretty much par for the course. Until recently, most dive watches used replaceable non-rechargeable batteries, and you'd always get the unit pressure tested when getting the batteries changed.
What I'm not clear on though is whether the pressure-test is non-destructive. Is it a matter that the results of the test would either be 'yes, your watch is still working, so it's still waterproof', or 'your watch now is dead and full of water, so the seals were compromised' - or do they have a way of telling before damage to the watch occurs? If not, unless you're actually planning to expose the watch to high pressures (e.g. scuba diving) or have good reason to believe the seals will be damaged, then you might not want to take the risk of testing it. Plus, depending on how they offer this service in terms of price and warrantees, if might be quicker/cheaper to get it done at a specialist dive shop that offers pressure testing.