Why would a man who doesn't want children, contact a woman who does? ?

MAYBE HE REALLY NEIN KNOWETH HOW TO READ:

Hi Jane, it would appear that John is somewhat driving you bonkers trying to gain your attention despite not being remotely anywhere near a potential suitor for you. He's just one of those billions of guys using such forums to hopefully get his balls wet on a regular basis! That said, despite you making it very clear of your expectations billions of boys/men/neanderthals will still chase after you as many believe that a very large percentage of girls/women using these forums are extremely desperate which I know is not the case. However, your age (Which in my eyes is still very young) possibly works against you especially with them knowing that you want children which potentially might afford them the opportunity to get a date with you as your body clock is against you! So, I wish you the very best in your pursuit to find happiness as it's not going to be easy.

Sadly, many men on these sites are only looking for women to have sex with.  They don't want to commit to anything long term, so they don't care if a woman wants to have kids.

That's why I don't do online dating

Men on dating sites are looking for sex. they aren't looking to marry you or have kids with you and they say the same thing to everyone they contact about reading their profile