Yeah, that sounds like a fine plan. It's not odd really for a newly built house/garage. Many states are instituting requirements to pre-wire for being "EV Ready". Different states have different requirements for that. Some specify to put an outlet on, some not. But regardless, they need to get the wire in the wall before the sheet rock goes up, because that's the expensive part to retrofit later. Yes, it is legal--because of this: There is a specific code provision that allows this. And I think that may be one of the reasons why Tesla made the 2nd gen mobile connector only run at 32A max. There are a lot of these 50A outlet types on 40A circuits, and they did not want to be the cause of any problems of people drawing 40A from a 40A circuit, and risking problems if faulty breakers didn't cut that off.