If I was your boss (which won’t happen don’t worry; I don’t have the ambition to lead which is why I’m apparently so good at it) I would absolutely demand you explain every hypothetical in every conceivable detail before I’d make any sort of judgement.
The number behind is not the real phone number from the boss, but a forwarding number. If you send a message to the number, the message gets in a queue for the boss to read and he will see the message when he is back in office.
Actually: While these kinds of services exist, they would result in a green message box in iMessage. So here it's clearly just a joke between pals