Yep, sure do if they are an "adult". When Johnny turns 18, he is no longer a youth in a Boy Scout troop. He is a youth in Venturing (co-ed 14-21 BSA program). So at 18 the "out" gay youth is no longer welcome in the troop, but can still participate as a Venturing youth until he turns 21.
But it gets better... we also discriminate against those that do not agree that there is a "higher power" in the universe. Catholic, Jewish, Buddist, Mormon, Muslim, Wiccan, etc. All these believe in a "higher power", so they are all welcome in BSA.
I didn't realize that, I thought they passed a resolution that gay men could be Scout leaders. What happened to that guy who brought the law suit a couple years back?