It could be required by the company. Many companies require top executives to have personal security. I'd be surprised if Zuck didn't have bodyguards even within the office. He has 24/7 security outside, so why wouldn't he inside?
I think the notes about Alexander I’ve heard is just how obvious his were
Yeah, like all the tech CEOs surely have bodyguards, but they try to blend in and not be noticeable as bodyguards; sounds like these were trying to make a certain impression?