Surely, regardless of what you have or haven’t done, if someone is yelling at you to get on the floor or I shoot and is pointing a gun at you, you get on the floor?!
I have absolutely no idea what I'd do in that situation. I've never had a gun pointed at me. Maybe I'd comply, or maybe the mortal terror would completely override the rational parts of my brain.
Ever watched one of those TV dramas where someone's told they're terminally ill and they suddenly stop hearing a word the doctor's saying? Sometimes it actually happens in the real world, that intense emotions like fear stop you taking anything in or processing any information.
How about fight, flight or freeze? We evolved around deadly threats that resulted in emergency responses we can't easily control without training, and none of these automatic responses are "immediately and calmly comply with the barely comprehensible screamed instructions coming from the deadly threat".
I'd be surprised if an ex-member of the Armed Forces didn't have an understanding of the wide range of human responses to fear and crisis, and the amount of training it takes to reliably override them. You might be able to think straight with a gun pointed at you, but I'm a random member of the public, and am not trained in assessing threats, remaining calm in life-threatening situations, or de-escalation (all the things that I'd hope a police firearms officer would be trained in).
When it comes to this kind of yelling and gun-pointing thing, I've seen occasional footage from the UK, but the US produces seemingly endless clips of aggressive police yelling incomprehensible, incoherent, sometimes contradictory commands while pointing guns at terrified members of the public, who end up dead.
There are a lot of factors contributing to this, but I think part of it is the result of a kind of weird, topsy-turvy allocation of responsibility.
Some US police are apparently conditioned by paranoid training programmes to overestimate threat, seem to be prone to volatility in a crisis, and have all kinds of allowances made for deadly violence if they just claim they felt threatened. They're held to a lower standard when on duty than the general public — they're almost never criminally prosecuted for their actions, for various reasons, and "qualified immunity" means it's virtually impossible to pursue civil action.
Random untrained members of the public, meanwhile, are expected to remain calm and rational when in fear for their lives, being threatened by armed officers who would likely face few repercussions for killing them. They're made responsible for de-escalating incredibly tense, deadly situations they've had no training in. And while police go about knowing that anything they do to a member of the public will be treated more leniently than usual, members of the public know anything they do to a police officer is categorised as a far more serious offence than the same action against an ordinary person.
Although there are more problems with US policing than the apparent assumption that it's okay to kill someone if they don't react quite right when you point a gun at them and scream, I don't think it really helps.
Also, what if the person's deaf, or autistic, or has dementia, or doesn't speak the language?