It's not disingenuous. Maybe not you personally, but you know damn well there's a large number of people who are against trans athletes simply out of bigotry and are not open to any compromise or regulations to make the game more fair at all.
No one in their right mind thinks Lebron James should be able to go to the WNBA overnight. But if the right amount of treatment is done to minimize the advantage to as little as possible or ideally 0, then who cares?
And it's worth noting that it's only ever trans women that seem to get the hate. Would you really want a trans man to compete in women's sports just because they were born a biological women? Of course not, that wouldn't be fair