I think you’re drastically underestimating the dynamics of youth culture and what it means socially to be the worst kid on the team. I’m not talking about the average player, or the star. I’m talking about the kid who has no athletic ability whatsoever. If your kid had trouble reading, would you sign them up for the spelling bee?
This happens all the time, of course. I just don’t think you’re doing anyone any favors. Just because you think it’s a great idea, doesn’t mean the other seven year olds will think so.