What a ridiculous strawman, it's clear you have neither an understanding of the issue nor of the gender critical position (if that's what you mean by "mumsnet" in this context.
The GC position is that gender is always nonsense, and has no bearing on anything. We are only interested in whether someone is male or female, which is determined by one's sex.
DSDs are tangentially related to the issue of transgender matters because some people may choose to be more sympathetic to someone with a DSD choosing to express themselves that don't relate to their chromosomes.
But sport is completely different, and is a matter of integrity, fairness and safety. This is wholly related to biology.
There is comprehensive evidence, both from ISO accredited labs, the boxer's own trainers, and our own eyes that these people are male, and they don't have the right to be in women's sports.
It's sad that you would construct a strawman argument, it's so obvious it's comical.