Because it is an idiotic idea.
Chauvin had three possible defenses to the charges. Everyone, especially cops does. The first option is proving that the defendant didn’t kill the victim. For Chauvin that would be finding a coroner who would say that it was drugs or any other cause. The Defense Expert was as close as they got. And his testimony on cross examination was the final nail in the coffin.
The second way is to demonstrate that the actions taken were in self defense, or otherwise justified by circumstance. That was out the window because Floyd was handcuffed.
Lastly, as a cop, you can demonstrate you were doing what you were taught and trained to do.
The knee technique was authorized, until the suspect was restrained. Chauvin was violating policy by maintaining the position after that. The person who trained him testified that yes, he had explained it to Chauvin during the training course.
Your idiotic idea was disallowed because you can’t do dangerous things in court. This rule goes back to a case during the old west. A man was accused of murder. The Defense argument was that the man carried his pistol butt forward requiring a twist draw. It was possible to shoot yourself. This was before the discovery of rifling distinctiveness. The lawyer thought the pistol was empty and shot himself. He died, his client was acquitted.
On this date, Clement Vallandigham, a Representative who was eventually convicted of treason, was born in Ohio. The son of a Presbyterian minister, Vallandigham eventually became a prominent lawyer in a thriving practice in Dayton. A believer in states’ rights, low tariffs, and slavery...
history.house.gov
For your idiotic demonstration to work, the Prosecution would get to choose the person kneeling on Chauvin. If I was the Prosecutor, I’d choose someone from Floyd’s family or friends and let them murder the Defendant right there in the courtroom.
If you were half as smart as you claim you would know that the demonstration would be suicide for Chauvin.