Haha...no the bathroom at this hotel is literally right next to the door, I can hear my neighbors walking into their rooms sometimes when I stay here so I would definitely have heard a knock. Especially since the guy entered twice.

And yes (to everyone suggesting using door lock) I will be using the door bolt from now on - honestly is just something I never considered using before in my 350+ nights staying at SPG hotels. This is the first time anything like this has happened.