When I rule the world, this will happen...
We will stop pandering to people. There is a simple biological fact here which should be the only deciding factor, and it's the existence of the Y chromosome. I don't actually care if testing for it is "humiliating." Athletes all submit to routine doping tests now anyway, and if they want to compete at an elite level, with all the opportunities, fame and rewards that brings, then tough, they need to have the test. Andy Murray had to take a random drug test just as he was leaving his house to go and be knighted by the Queen or something ffs, and he just got on with it.
If you have a Y chromosome, you cannot compete in women's sport. You compete in men's sport (that takes care of the likes of Rachael McKinnon as well). If you have no Y chromosome, you compete in women's sport.
Which would mean that Caster would not be able to compete in women's sport regardless of whether it's 800m, 5000m etc.
Sure it's unfair to the very small number of people, like Caster, who were raised as girls but later turn out to be intesex / have a Y chromosome, but fairness to the majority of people has to be the first consideration. It's "unfair" to transwomen (and transmen, although we don't really hear about transmen wanting to compete in men's sport), but it is fair to women.
Incidentally, I did feel sorry for Caster initially - I mean, what a bloody shock, finding out in the public eye that you weren't what you thought you were. However, she's had 10 years to come to terms with this, and she now needs to stop throwing women under the bus to fulfil her own selfish ambitions.
I'm happy for Caster to keep the medals and titles she won before she knew about her Y chromosome - she was innocent of any wrongdoing then.
And also incidentally, I don't believe that women (i.e. XX chromosomes) with naturally-occurring higher-than-average testosterone levels should have to lower them in order to compete in sport, but I do think there needs to be testing of testosterone levels to check that doping isn't happening.
Hard cases make bad law.