Why do you talk about "right car" if there's no config options except 6 colors...? Ok, 2 type of wheels makes 12 different cars. AP and FSD are just software options. If they have a few in stock they have the right car for everyone.
The point @ggr was trying to refute IMHO is that Tesla would have picked this person because he had just the right config which they wanted to deliver and didn´t find an S/X owner for. So your argument really points in the same direction as his in that this doesn´t make sense - neither did they know before they picked him what he´d configure nor are the configurations specific enough they´d likely have trouble to find someone to deliver it to.