He could have told you: "sorry I fell asleep, I need some extra mins to get ready for you see you at 5:30..."
It's a competitive market out there, I don't think he got an overnight starting at 6 PM and therefore made the choice to see another client instead of you, besides he's cancelling at 4:39 for 5 PM?
I understand (but never justify) when clients are flaky but when escorts do it.. it just makes no senses from the business point of view besides they don't know who they're dealing with. Some folks out there could get sore and review him or set a fake appointment to "get back" at him.
Sorry this happened to you!