To clarify the earlier clarification, 
, the NLI program is governed by Collegiate Commissioners Association. The NCAA does handle the paperwork, but the form and content of the NLI is set by the CCA. If disputes occur, the matter is resolved within the CCA, and not by the NCAA. There is a recruiting ban, as Rick says, but it is not part of the NCAA rules, and coaches at non-participating colleges (think Ivys, Patriot League, and service academies) are free to continue recruiting. If a coach at a participating school does recruit in spite of the ban, there are no repercussions from the NCAA. Instead, the coach would be violating the agreements his institution have with the NLI program, and any recourse would be determined by the CCA..
In the situation affecting the OP, once the NLI school makes known that they wish to back out, immediate recruitment by other schools benefits everyone, especially the NLI school. Realistically, the CCA is not going to do anything to discipline the recruiting schools in this situation. After all, a primary purpose of the NLI is to stop schools from poaching another school's recruits. In this situation, the NLI school wants just the opposite.
I bring this up partially because people may suppose if the OP's son were to not ask for a release, and enrolled at his NLI school, but the school refused to award a scholarship, then some NCAA rule would have been broken. Instead the OP's only recourse would be a suit to recover the cost of the promised scholarship. The NLI is a contract between school and player. The NCAA is not involved or responsible, unless it makes an error with the paperwork.