Whether or not the SC can do a door alignment properly depends on experience, tooling, and the nature of the misalignment.
For example, the Tesla SC may look at this door and think “Ha, easy, I’ll just move the striker in and up 1mm or two.” That could be the appropriate remedy, but it’s more likely that the entire door needs to be shifted up on its hinges. Align one door in this manner and you need to do the front door as well, after finishing the front door you may need to do the fender. After all that you may need to adjust strikers. OK, great, now the car looks perfect, but wait, now it’s super loud on the freeway…Oh, dang, my doors don’t seal properly anymore.
Door adjustments can be trivial but often they are not. That’s why I let a body shop do it.
As for “letting them try”, I prefer not to waste time. Whether or not someone is willing do this depends on many factors too.