Nothing, that's why this comes off as largely performative and awfully suspect.

Let me put it this way - these labs are functionally pretty similar to a Qwest diagnostics or Lab Corp. Those places draw your blood and run tests on it. The prescription tells them the tests to do, and the doctor is the one who evaluates the results. The labs are just a dumb tool to do the testing as prescribed.

Donut in this case is writing their own prescription and then posting the results. Just like a lab, they don't interrogate you to see if you are manipulating your blood results. That's the doctor's job. And ultimately at the lab it's just a lowly tech going through the same motions they go through every day.