The problem is not that the Boy Scouts have allowed the young boy members to participate regardless of orientation as most of them shouldn't be engaged in any kind of sexual practices whether they are homosexual practices or heterosexual practices. The problem is that this decision fundamentally changes their pledge and their values.
The boy scout pledge to:
"On my honor I will do my best To do my duty to God and my country and to obey the Scout Law; To help other people at all times; To keep myself physically strong, mentally awake, and morally straight."
has now been compromised. I can guarantee the the same pressure that forced this decision will be continually levied against the boy scouts to redefine "morally straight" in such a way as to allow, and even promote, same sex relationships.
Then, once that has been done, those exerting pressure will point out that it is inconsistent to allow moral straightness to include same sex relationships and yet disallow scout leaders who are engaged in same sex relationships.
This isn't the last we have heard on the issue because those who desire to make sure that everyone in america celebrates same sex relationships will not stop until every organization celebrates it, every church embraces it, and every person who dares speak to the contrary is criminalized.