To support one is to legitimise the other.
Older male / young female or older female / young male is a distinction without a difference. Neither males nor females are mature enough to nurture and support a child while they are minors. Nor are they disciplined enough to juggle active sexuality while meeting their obligations.
It’s a firecracker with two fuses. It doesn’t matter which fuse you light.
Many would disagree, including the legislators from my youth. As I recall, if I had dallied with a girl just under 18 when I was just over 18, that would have been very bad. In contrast, the law said nothing about me dating an 18 y/o when I was 17. The courts eventually ruled that the distinction was sexist, but I disagree. The rules should be at least somewhat different for men and for women, with boys and with girls (but not for teacher/student).
Note: I also very strongly disapprove of any school teacher of any age dating any of his/her students of any age, and in general of professors dating their students regardless of age.