That's possible.
I knew an old security guard who would keep his magazine loose in his holstered gun. His reasoning being that if he had to draw, he knew about it and could slap secure in a fraction of a second, but if someone took his gun, they wouldn't and the magazine would fall out, throwing them off and buying others more time.
But that is my theory is that the magazine is not secured at all when he walks on camera and he's using his right hand to "hold" it in place before letting it go. You make a compelling argument for your alternative though I'll grant you that.