The implication of this is that a trans woman who hasn’t devoted her life to the sport will be able to compete at the highest levels
There’s no such implication. They’d still have to train, but there’d be an inherent advantage. A common example used to justify the division of sports between male and female categories is grip strength – the female world record is ~65kg, whereas the male average is ~50kg. A trans woman who underwent male puberty would have an unfair advantage, on average.