They did this for two reasons: 1) It made them feel important, and part of a high-level caper. They were definitely thinking this will be an exciting part of the inevitable movie, especially when they dramatize it all up.
And 2) It was a propaganda stunt, made to look like his life is in serious danger from the Iranians (I wish), and his handlers are clever operatives who can conceive and pull off a dangerous stunt to protect the president, even though he wasn't in danger from the Iranians, and the stunt wasn't dangerous for the president. He's too fat and slow and stupid to survive anything dangerous.
The only people they fooled were the press pool, and even they knew something stupid was up, when they made them all close their windows AFTER the adventure was over, for some reason, which only alerted the press that something weird was going on. Otherwise, they never would have known. But it's no fun to fool people who never know they've been fooled. It's only fun when they know they've been had, and you can point and laugh in their faces.
And it worked. The news covered it, and even called it extraordinary, even though it was just a propaganda stunt, just more MAGA shenanigans.