It is understood that this is an unstable, temporary step until the BSA "goes all the way" and allows homosexual adult leaders. Within a year scouts claiming to be homosexual will turn eighteen and apply to be adult leaders. The BSA will have no coherent argument to deny them.
Furthermore, the new policy was designed to destroy the defense which the Scouts successfully used years ago to restrict homosexuals from leadership. That was the argument that a private organization could vindicate its own uniformly applied membership principles. Now the BSA can't say that anymore.
It seems to me that the BSA compromised their principles severely, not to mention, as others have pointed out, failed those parts of the Scout Oath which say that a Scout is brave, trustworthy, reverent.
What the Council did was unforgivable and shortsighted for exactly the reasons you describe.
My kid just became a Boy Scout after 3 years as a Cub. It was a tough call to leave him in the organization but the decision at the National level has had no impact on his Troop, everything is status quo.
The future of Scouting however, is very dim.