Anti vaxers believe "science is on their side" as do climate change deniers. The trick is to use the evidence selectively and pick only the papers that support you (or only the parts of papers), that way you can claim to have scientific support even when you actually don't.
Rachel is probably referring to a couple of studies of Olympic athletes that support the idea that the variation in natural testosterone levels for male athletes does not have an effect on performance. However, those studies found that testosterone levels DO have a beneficial effect for women in certain events, which is why the IOC recently reintroduced a limit on testosterone levels for women athletes.
Either way, those studies aren't relevant as Rachel went through puberty with XY chromosomes, meaning that some physiological differences are always going to be present.
Someone on another thread pointed out how you don't see trans women gymnasts competing at the highest level. That's because they have a different physiology. Women have greater flexibility in their joints, which means their events are different to those of male bodied competitors. Those back arches you see on the beam? Trans women can't do those.
Male bodied athletes have advantages in terms of a lower fat percentage, larger lungs and a larger heart. They are also less likely to suffer shoulder and knee injuries. They are, statistically speaking, taller too. For trans women to compete on a level playing field with women, you'd need to eliminate those differences - but even trans women who lower their testosterone level and take estrogen will still have larger lungs, a bigger heart and be, on average, taller.
Truth is, science has not conclusively demonstrated the idea that trans women athletes do not have a psysiological advantage over those born women. Because there is quite a lot of natural variation within the groups, you need a decent sample size of trans women to use as a comparison. This hasn't happened yet. The nul hypothesis is that they DO have an advantage, as we know conclusively that those born male have, on average, an advantage over those born female in most sporting events. To guarantee fairness, we have to demonstrate that trans women do not have an advantage.
My feeling is that trans women should have their own events. They can then compete at the highest level on the biggest stages, and also we will be able to gather evidence to see if they retain an advantage or not.
Interesting reading:
blogs.bmj.com/bjsm/2018/04/11/time-to-dispense-with-the-male-female-binary-in-sport-analysis-of-the-cases-of-laurel-hubbard-and-mack-beggs/
On a side note, this is another example of the BBC failing to fact-check the use of science. They are not alone, but they do seem particularly bad at challenging incorrect scientific claims. By prioritising so-called balance, they allow a minority position to make unscientific claims and do not call out those unscientific claims. If the interviewer had done their research and was being objective they would have pointed out that the scientific community, as a whole, does not accept the idea that trans women are women in sport.