There's not even a single reason there, let alone many.

Older people get married past the age of childbirth, infertile or avowed child-free opposite-sex couples marry too.

The 'signal' is already hopelessy noisy and not fit for any sort of purpose. Plus, "we were using those numbers for something they are inherently unsuitable for" is no valid reason to continue discrimination.

At this point it really looks like you're grasping at straws to justify what is just a prejudice.