Hahaha, that's a really strange, absolutist statement. People make those decisions all the time without even realizing it. Painting them all as bad parents is really ignorant.

And, all else being equal, why does it matter if that's a factor? Do you assume that women are less qualified or that they'd choose a doctor who wasn't qualified just because of their gender? Also, you think the mother should be uncomfortable whenever she takes the child to the appointments? Why wouldn't parental comfort with a physician be a factor in choosing?

I think you can understand how implying they are untrustworthy to her could cause issues if she was in an emergency medical situation in which the attending physician is male. You're unlikely to take what I say into account, but hopefully someone else reading this will, I guess.