To the casual observer, this thread reads like you have a preference for MIT over Caltech, and you don’t want to close the door on MIT even though the soccer coach has been unambiguously not interested.
Obviously I don’t know your intentions. But if I were on the coaching staff at Caltech and saw this thread, I would be concerned about your resolve to honor your commitment. Keep in mind that this is a public forum, and anyone at Caltech who knows the incoming class of soccer recruits would know exactly who you are from reading your posts.
Hopefully your son is clear about his commitment, and your thoughts here are just those of a parent who is still attached to the idea of MIT. But I agree with the others who have cautioned you about unintended consequences.
Congrats on Caltech. BTW, compare the current weather in Cambridge and Pasadena. Where would you rather be at soccer practice? 