I haven't looked at GTI manual so if it says ok for center latch, go for it. If not, it wasn't designed that way and shouldn't be done. The anchors are spaced a specific way so the seat doesn't fly all over the inside of the car in an impact.
https://thecarseatlady.com/vehicles/latch/center-latch/
Note that Uppababy says "In order to use the rear center seating position with lower anchor, the distance between the lower anchors may be up to 559 mm (22 in) and the seating position must be approved by the vehicle manufacturer. If spacing between the lower anchors is greater than 559 mm (22 in) or if the seating position is not approved by the vehicle manufacturer for use with lower anchors then use the vehicle seat belt for installation."
So, no more than 22" but also approved by the manufacturer. Who for the GTI says outboard seats only. I hear you on the perception of the physics, but if its not approved its either not been tested or been tested & doesn't work. Either way, you & your newborn would be the test environment, when you're needing it to work.
It is possible to get the seat just as secure with the seat belts as it is with the LATCH system. It can be a bit of a pain to do it. Personally - I always used the centre position with my kids, with the seat belts.
Theres also a searchable link on NHTSA for a seat install check (often the local fire or police department):
https://www.nhtsa.gov/equipment/car-seats-and-booster-seats#install-inspection
Good luck with your new arrival!