If we all zoom out and take a look at this, it's all very silly.
Semenya is a woman, who should get to run against women.
Those arguing against that inevitably say that female runners are being treated unfairly by her participation in their events.
The only people that could remotely have any problem with her running would be: countrymates who miss out on representing in international championships due to her presence, athletes who fail to advance to a semi or final because of her presence, athletes who place one spot lower in a final due to her presence, athletes who are unable to join an international race field or finish one spot lower due to her presence.
In total, you are talking about maybe 5 or 6 individuals being effected by this every year. And even though they may take some kind of financial hit, they are ultimately committing themselves to a sport where that is a possibility. No one is entitled to get an Olympic medal or even qualify for the final.
The sport as a whole is better when athletes at the top of their game get to dominate. I would much rather watch Semenya run 1:54 and crush a field than watch a bunch of runners run 1:58 and finish in a cluster. It's the same with the men's 800 where Rudisha running 1:41 or Brazier running 1:42 and dominating is better than a blanket finish of 1:44-1:45 guys.
At the very least, don't you want to see the best runners compete at their best?