He's missing the point - women don't suffer because they have children - they suffer prejudice simply because they MIGHT have children. It just happens to become more obvious once they do actually have children whereas it's more of a hidden prejudice prior to that. It's a much bigger issue that he thinks or than many realise.
The prejudice starts from the moment a woman of child bearing age attends the first interview and carries on every time promotion is considered. It's so ingrained that a lot of employers aren't even aware that they do it. Single, childfree man hoping for a partnership - not a problem. Single childfree woman hoping for a partnership - only after the employer has weighed up the risks of whether you might take time off for maternity leave, you might not come back, you might have more than one lot of maternity leave, you'll only want to work part time, you won't be ambitious anymore - suddenly offering partnership to a woman is a minefield that employers can't navigate.
As for women who don't have children - well, given that it can happen even in a woman's 40s, employers still consider the child free ones risky as well. So he's completely wrong that childfree women do as well as men and sexist again because he's not comparing like for like.
He is comparing a childfree woman to a man, not a childfree man, but any man, because children generally have no impact on a man's career. He's also missing the point that a childfree woman may have had to choose between a career and children, unlike the majority of men.
It's not going to be an easy change, not because of biological reasons, but because it requires an active change by men. Men actually need to do something about this such as taking parental leave and genuinely believing that they should be an equal parent.
Of course it's inconvenient as an employer to have someone take time off but it's a fact of life and the only way to stop women being penalised for it is for employers to realise that men are equally likely to require time off. But as I said, that requires men to actually take the time off, both at birth and for sickness, school plays, etc etc. I have no doubt that it will only be once men starting taking significant time off that there will be any change to the culture of Mon-Fri 9-5 and presenteeism because employers will need to adjust. There's just no incentive to do so until men start asking for change. How thoroughly depressing.
And yy to bellend. And that lets him off lightly.