DCM In Lawrence V Texas the Supreme Court of the US ruled that Homosexual acts between consenting adults were lawful.
To say that leads to a man being able to have sex with a 13 year old girl is ridiculous!
The court will not approve that because a child can not give legal informed consent. When that becomes the issue I am on your side. But it is not the issue.
For an analogy you are saying raising the speed limit on some highways from 55 to 75 will make people drive drunk or drive 75 in school zones. They are two separate things. One is reasonable and non-harmful to others and the other hurts and kills innocent people.