I clearly agree that there is a difference between being gay and being a pedophile (although clearly one could be both as one hears horror stories of boys being molested by men).
The concern would be a conspiracy between two pedophiles (gay or no) to use liberalized adoption laws to victimize children. In other words it would not be a random occurrence but an intentional crime therefore the math fails to represent the threat).
For example the child molesters who joined the Roman Catholic church as priests to victimize children created a greater concentration than random collection in the general public. It would still be a small percentage but the damage/horror done to the innocent would be an abomination.