When somebody's born, they don't identify as a gender. By the time they reach talking infancy, they do and will tell you. They will probably want to adopt gendered clothing and behaviours. Those might, or might not match their anatomy. If they pick cross-gendered ones, that might last, or it might go away, or it might turn into gay/lesbian identity. If you aren't being pushy about any of this, they will find their own level. I am not proposing "never permit them a gender", I am proposing "never assign them a gender, coercively".

Unfortunately with strangers, I have less evidence about their genders than I might like. That is because people don't feel very free to express cross-gender presentation, and in fact it takes such an immense crushing need that people dare the taunts, for them to even be visible. So there are lots of tans women walking around looking like men, and there are lots of trans men walking around looking like women. And it is because of dismissive attitudes like yours about the skirt, which easily translate into ridicule and ostracism. A boy in skirt is not like a boy with underpants on his head, he's like a girl in jeans. That used to be scandalous. But we accepted it more readily, because dressing "like a girl" is seen as degrading while dressing "like a man" was seen as upgrading.

You are strawmanning "ignoring the biological gender" (and building upon an assumption that isn't true; biology isn't gender, it isn't even oversimplified binary sex - but that's a story for another day). I am not suggesting "ignoring" it, I am suggesting "not treating it as the thing that determines gender".

I'm still unclear as to why ignoring the biological gender of your child will help them be more tolerant in later life.

Solving this type of problem is one reason that I advocate differentiating gender and biological sex. Once that distinction is made, I think many of these problems are analytically clearer.

FWIW, I think JulianMorrison is using "gender" when "sex" is meant in at least some of the comments.