Possibly because it works for some women, like Jess Ennis and Jo Pavey.
Volleyball, tennis, swimming, weight lifting, marathons, triathlons... an ever growing list of elite female athletes coming back to top flight competition, both endurance and sprint, team and individual.
There is some new research, well, sort of, looking at how female bodies react to elite training post childbirth. If the perceived results are born out then it could mean that many more female athletes will not have the cut and dried choice - child or sport!
So we don't know the wider context that any such conversation took place in. Maybe British Cycling is sexist... maybe some women do voice their doubts and get different advice from coaches... maybe some athletes just don't like to be told they have lost their edge!
Oh... and before anyone shouts about the 'fat' comments... body fat% is a widely used measure that directly reflects changes in fitness levels. Women are, by nature, more prone to changes in mid 20s - more research is ongoing!
Always assuming that such a gender bias is allowed, of course!