Statistically homosexuals overepresent themselves in committing sex crimes. They may be 3% of the total population, but they commit 30% of all sex crimes. That is overepresentation. Not sure if the 30% is spot on, could be more, could be less, but it is more than the 3% figure that they represent in total population. Homosexuals, by the numbers, are sex crime overachievers. Not all are so, but they do have a disproportionate number.
Again, the BSA has had far more lawsuits and far more grief with heterosexual sexual predators and pedophiles than homosexual ones. The BSA does not take their moral stand against homosexuals soley on litigation protection. In fact, if the rules for leadership conduct were strictly obeyed, homosexuals could not have the opportunity to commit any crimes. Child safety is enforced to keep all leaders in Scouts out of any possibility of inapropriate behavior.
Avowed homosexuals is a different matter. The BSA says, simply that they believe that promotion of a homosexual lifestyle is incongruent to traditional and tested parenting models that develop fathers and mothers.
There are in fact some homosexuals in Scouting, just like there are some heterosexual pedophiles in Scouting. The BSA has made rules of conduct and policies that if followed, will allow such people to still be successful Scout leaders. Only when rules are broken, are both gays and straights kicked out.
Additionally when a person avows homosexuality they are out on a mentoring principle, not because they may cause harm to children. In fact, many homosexuals that have "come out" and avowed their lifestyle were exemplary leaders for many years in Scouting that would never cause harm to any child.