Yep, definitely a security issue. I would have shot the intruder dead, therefore making him very easy to locate. Not sure if a concealed weapons permit is a valid option for your friend, and regardless it won't help the current situation, but it does provide a feeling of security in case that were to happen again.
Let's not turn this is into a gun issue.
Is there a bypass key for the lock? If so, the lock could have been picked. Paper could have been wadded up into the catch to make the latch only partially catch. From there, it is easy to use a piece of flexible plastic to work the catch back? Was it a room with a locked internal door to another room. What about a balcony?
Your big thing is to find out how many incidents. Also you might wish to file a police report. Hotels want to keep this internal.