1) He is properly credentialed to claim expertise in his field
2) He is trained and qualified to apply the scientific testing standards of that field
3) He met those standards while conducting his tests
4) He subjected his research to the rigors and scrutiny of scientific peer review.
So far you have demonstrated none of these four things. Incidentally, in all four areas he is also suspect.
In a sense, human reaction time doesn’t matter a lot. If someone is 30 feet from you and they rush you, then maybe you will get a shot off - depends on your speed. But a determined bad guy WILL survive the shot in almost all cases and be able to stick a knife in you - or shoot you. If you remain stationary, there is no viable way with a handgun of any size to prevent the bad guy from shooting you, and probably not from stabbing you.
That is part of why cops need to accept some risk. If you can shoot him, then he can return fire in almost every case if he is determined to do so. That is true for at least 10 seconds and often more.
In this case, the cops COULD have maintained a discrete distance, get closer to the guy as he approached his car and ordered him to stop and raise his hands while they were protected by cars between him and them. ONE guy might have to close to a more dangerous range - but if he doesn’t have a gun in hand, they will have the advantage.
The cops could not have handled it worse.