But dude even you said yourself that the AI was on easy! And if you carry on watching that BM clip he uses coins to an equally absurd effect. It is a funny clip for sure, but not an anomaly for the series' AI.
Like I added to my post already:
The difficulty menu doesn't list "improved AI", it just lists "AI reacts FASTER". Which means the AI will react exactly this way all the time. Contracts had totally different AI for the higher difficulties, but it doesn't seem to be that way in this game.
And if you can't see the difference between getting hit by a coin and a fire extinguisher, then I really can't help. I'm not even sure, maybe the AI in Blood Money reacted to coins getting throwing directly at them. I would have to boot up BM to try it out.
If the Absolution AI was done well, the AI would have raised an alarm in this case.