I actually agree with the gays here. We didn't want the Boy Scouts to be forced to admit gays, and we shouldn't turn around and demand that a gay gathering be forced to admit opponents - and that is what this group is doing, saying they will enter a private gathering against the wishes of the organizers.
Boy Scout clubs are private entities. Public marches and parades are not.
However noble the sentiment is, the law of the land is that you must accept imposition. This is the rules THEY set up. It is just holding THEM to THEIR rules. (no different than the 5th columnists using the bill of rights to undo the bill of rights)
Forcing the issue to the contrary may actually do some good by shedding light on the reasonableness of the Boy Scouts position.
you leave 98.3% of the population alone and you can do whatever you want to yourselves behind closed doors.