It doesn't matter what the mark wants to do. It is the job of SS and EP agents to take control and remove the mark from the scene as soon as it is safe to do so. It usually takes time to declare an active scene safe. The fact that he got up, fist pumped posing for the camera and crowd within a minute of shots fired is highly unusual. The reason being, that there could be other shooters/attackers. However, I am not a wackjob conspiracy theorist, so I look forward to more details as they become available.
1. Trump probably tells the secret service what to do. And they listen even reluctantly sometimes.
2. The FBI is going to be the investigators so they will make up any bullshit they want. 3 letter agencies are all deepstate controlled. They will make up whatever situation they choose.
A blonde woman in a cap in the audience behind him drops very quickly. Initially though she was shot too. Reserving judgment too though.