All I can say is that he is 11 NOT 5. At 11 I wouldn’t have been fooled for a second. I would likely have laughed.
At eleven, unless your dad was a serviceman or LEO, you probably didn’t worry much about people wanting to kill your dad.
I’m glad to know that you’ve never been in a situation where you realized that evil people want to hurt your family.
It’s a privileged experience these days.
My oldest daughter just turned 11. If she knew that people constantly threatened to kill me, and she saw on TV someone holding what appeared to be my severed head, her initial reaction would be to fear the worst and call for her mom. I’m sure that she’d soon realize that that couldn’t be real, but for those first few seconds she’d be in distress. And that would be true even though I’m not living in DC while she’s in NYC so she would have seen me in person that morning.