It might be best if he first contacted the school counselor to discuss this issue. They could help him to determine whether or not it is the right time to “come out” to his parents. If they are as unsupportive as you say they are, it may not be the right time. The school counselor will help him to know what to do. They will also ensure that he receives counseling, if necessary.
Regarding mental health treatment and related services, each state has different laws regarding age of treatment consent. In some states, minors of a particular age (some as young as 14) can give consent for services. The school counselor may have more information regarding age of consent for mental health and related services in the state of Minnesota. I hope this helps you know how to proceed.
His parents may never fully accept his being gay. Perhaps they will and hopefully there will be a positive outcome. He is lucky to have your support. No matter what happens, counseling is highly recommended. It will provide him the additional support he may need for dealing with his parents and other ill-informed individuals in this world. Good luck and please take care.
Dr. Kristina Randle