He's a pedophile.
Some pedophiles experience attraction to both adults and children, and oftentimes, their sexual preference for adults is independent of their sexual preference for children (and often they don't even have a preference for the latter). However, true pedophiles exclusively desire children, even if they have adult relationships as a sort of "cover."
So, there doesn't appear to be any consistent correlation between sexual preference and the sex of their child victims.
As an example of this, here's just the straight-up numbers: almost all pedophiles are men. About 1/3 of them prey on male children. But only about 2-5% of the population is gay. So obviously, there's a lot more pedophiles who molest male children than there are gay people.
The reason for this may be because, socially, a man has more access to male children than he does female children. Pedophiles usually molest children they know. So this could be a family member (who would have access to children of either sex), but also something like a scout leader, or a coach, who would probably only have access to male children.
Pedophiles are fundamentally opportunistic. Some do prefer one sex over another, but their primary attraction is to children.