In this case, Tesla actually might put it in a showroom with no qualms. Tesla in general does not particularly value fit and finish. That's not their car's selling point. That's why they have done little to address it.
Seriously, when they provided loaners to the auto press, they basically make no effort to pick a car that had good fit and finish (unlike other automakers which actual put effort to their loaner pool). That's why you have so many reviews where poor fit and finish is mentioned. A showroom car, they would care even less.
The absolute tolerances are not actually too loose, but rather to industry standard (even for premium/luxury cars like Mercedes, as I found below). Average gap size of roughly 3 to 4mm (not talking about variance here, but the absolute average) is quite common according to this post (edit: found the source, it appears to be Car & Driver's December issue, but the link seems to be dead):
Panel Gap Study
PressReader.com - Your favorite newspapers and magazines.
I googled a bit to try to find allowed variance numbers for the hoods of cars.
Here's one for the current NB Mazda Miata (sold from 2015 and still a current model):
"The spec for hood to fender gap is 2.8 - 4.8 mm"
Panel gap by hood/front fenders?
Here's what it is for the current W205 Mercedes C-Class (sold from 2015 and still a current model):
"I believe it's 3.5mm for ( location C ) Engine hood to radiator trim/soft nose on a w205.0/1. (
± 1 mm)"
3.5mm +/- 1mm means 2.5 - 4.5 mm.
Noticeable hood/bumper gap - MBWorld.org Forums
You will notice how both is close to the 2-4mm spec that the service manager told you (in fact Tesla's spec would give an average tighter gap of 3mm vs 3.8 or 3.5). The 2mm allowed variation between the smallest and biggest gap seems to be industry standard. So there is nothing wrong with the spec itself, it's just it looks obvious when it doesn't match on both sides (someone in the Miata thread actually mentioned that).
As a side note, I failed to find the spec for a BMW, but did come across this thread in my search, where people pointed out it's not uncommon to have gaps on the hood on the F80 M3 (2014-2018, $60k-90k car according to the thread) not be symmetrical.
Hood/Bonnet gaps?
So in general I don't think it'll have really that big effect on resale value of cars, as most people don't look closely enough. It just might bother people who are more meticulous about things like this.
Just be warned Tesla might not do anything in the end, as technically it's "in spec". A nicer service center might just do it as "good will", but they don't have to. As I mentioned upthread, it may be easier to just adjust yourself (especially the easier rubber stopper adjustments, which requires no tools and takes almost no effort), than waste time/energy on this.