My Son pulled himself out of Scouts for that very reason. It is sad he really enjoyed it, but his moral values no longer line up with Scouts. I am proud of him for taking a stand, he told his scout master why he was done. We are waiting for the 'hate calls', and nasty emails, from the liberal members of the troop.
If they come, just reply that the Scout Oath and Law are still the prime components of demonstrating Scout Spirit in their daily lives and hang up.
Then calls to all members of the Troop Committee and Chartering Organization are in order as the Scoutmaster would be the source of said harassment since he violated your son's confidence.
As a soon to be EX-Scoutmaster, I never divulge why a Scout left the Troop if it were for personal reasons. If one moves or transfers and another Scout asks, I'll tell them, but never when it involves something personal.
Best wishes to you and your son. I hope he finds something that will continue to promote the interests he has.
SZ