Who said anything about making judgement calls on his relationship with his parents? It doesn't matter what kind of car is in the garage or whether it's more or less important, the point was made that "if there are no issues with him living with his parents then it's fine". So I made the point that needing garage space and not having it constitutes an "issue" with living with his parents. It's pretty simple, actually.
I love my parents and they love me, but I wouldn't be able to cram both of my cars and all of my shit into their house while I came and lived with them. That's an "issue". It doesn't say anything about my relationship with them, it says I need my own place.