These people think she's not fuckable so therefore she's not a woman, and furthermore think women's sports are worthless unless they see the athletes as fuckable. That's it. It's patriarchy with a new coat of paint.
There is no trans woman in this case. A female boxer, born and raised as a woman, is being attacked and called a man. What OP is saying is that it's basically because they don't see her as attractive, and that's definitely a major component of it.
What it comes down to is that they're so obsessed with the idea of trans women that they start seeing them everywhere, and it usually comes down to someone not being quite feminine enough in some way, though there have been cases of people trying to claim some of the most conventionally attractive women in the world were secretly trans.
Are you forgetting the whole subculture of "transvestigation"? They were the Q-anon conspiracy theorists before Q-anon, and even Michelle Obama was claimed to be trans by this lot.
"It remains unclear what standards Khelif and Lin Yu Ting of Taiwan failed last year to lead to the disqualifications.
The IOC, which is overseeing the boxing competition in Paris, does not test for gender, and there never has been evidence that either Khelif or Lin had XY chromosomes or elevated levels of testosterone. They have competed for years, including at the Tokyo Olympics and several world championships."
Worth noting that the IBA is not considered credible by the IOC, is considered highly influenced by Russian corruption, and that this failure came just after she defeated a Russian.
Also, despite whatever tests she may have failed in the past, she passed eligibility tests to compete in these Olympics.