Before jumping to any conclusion, ask yourself, how did he manage to steal the key? and the answer is either staff left reception unattented, or left key in the open, unsecured
Next answer this, why hotel does not have spare set of keys? How unprofessional is that?
Next, once police was called, and did not arrive, why hotel did not call again?
Next, why hotel did not cut off electric? easily done.
Next, if he already stayed the night, again how unprofessional are the staff NOT to know their guests and available rooms.
After hearing owners voice and behavior, its hardly surprising this happened and if anything scary, hotel that does not provide any safety or security for the guests assuming what happened is true, as there is another possibility, which is staff skimming and selling rooms on the side