I agree that he never saw it coming - and your theory makes sense as to why he answered the door to this stranger. Can you leave a hotel door cracked like that? Someone knew he was there, that's a given to me. Tutti, I can agree on the pockets having something in them - could it be just the knife? Lol at the funny description of said bundled stranger - just amazing that he got through the hotel dressed like that, nobody at the door? Nobody noticed? He or she was so shady but managed to slip in and out.
If it has an additional dead lock on the door you can turn the deadlock to lock before closing the door and that will keep the door from shutting.