I know it is not the Boy Scouts.....however, one should have the right to free speech....they are American Citizens....and, I think it is gauranteed....
Freedom of movement, freedom of assembly, 4th and some 5th Amendment guarantees (and others) are ALL either vacated or limited when serving in the US Armed Forces.
You can't have service members publicly criticizing this or any Commander-in-Chief. It undermines authority and discipline.