Once committed, should a player still apply to other schools? How many?

The out-of-state school my son committed to does not have a fall early action/decision. There should not be an issue with admission since son will probably qualify for merit scholarship too with his grades and scores.However, since acceptances won't be out until spring, I told my son he probably should apply to two in-state schools that have a Nov 1 deadline just in case the program was cut (unlikely) or he woke up next spring and decided he didnt want to play his sport anymore. It is a very low probability, but I would want him to be accepted to some other schools just in case. However, son's ECs are basically his sport. Would admissions check with the coaches at the in state colleges because of that? He had offers from those schools; it might be awkward if admissions checked. He should be able to get in those other schools and get merit on his own. He won't tell the coaches he is applying to those schools since he declined their offers; he wouldnt want to explain it is a backup plan in case he wanted to go to college without playing sports.Because he verbally committed early, he had no applications in process yet, but he had written his essay. Would admissions already have a folder on him because he was a recruited athlete? I hope coaches do not give that info to admissions until a recruit actually applies. I dont know if he could be denied or deferred as he would be a yield risk if they knew he had declined an offer. Some schools do not want to offer admissions to students if they think they will be turned down. He fits the profile of accepted students at those schools. He visited the schools unofficially several times so it is not like he would be tracked due to an official visit.