That part makes sense. It seems to boil down to whether it's worth the risk. Tesla doesn't advertise, so having one of their cars in a neighborhood is the best advertising they can execute. While the SR won't be ubiquitous in lower-income areas, even a few will make a difference. A chunk of the advertising aspect could be covered by rental companies providing Teslas, so perhaps that point would balance out to a degree. There's still that perception that a Tesla is a snobby car, and I think the SR helps to reduce that a bit. If Steve down the road has a Tesla, maybe it's not just for The One Percent.
Tesla is also production constrained. They have a limited number of production lines for the Model 3. Each SR built in place of an LR is lost money.