If your son went through the process and was accepted to CalTech and he is happy with the results, full stop. Congrats! He has been accepted and should be focusing on moving forward with Caltech.
If the MIT coach did not get back to your son by text or email and did not show up for visits, that should be a pretty clear message from the coach about his level of interest; frustrating, but pretty definitive.
Again, congrats on CalTech and I hope your son has an awesome time in the classroom and on the soccer field there!