And if one were to be an eligible bachelor, what reason would one have to choose a single mom to date?
No reason at all.
If they're already pregnant with someone else's kid, you have total certainty they can't become pregnant off YOU and hit you for child support for the next 18 years (which happens with women -- they just say "I guess I forgot my birth control"). Of course, you would need to dump them as soon as they have the baby.