Did you try talking to the guy instead of simply assuming he is a creep because of his age? You should have tried to be friends to properly evaluate him and see if he is good for her. If you are worried about her becoming pregnant, a younger boy could potentially do that and be just as irresponsible.
I understand you being worried and concerned, I would be too. Not every pedo follows a girllove ethos. Some are looking for a girl to use only for sex or have as a slave to abuse and control. But you won't know who this guy is if you never talk to him.