I sleep with a handgun under my pillow while traveling and when at home. There are usually other guns within reach as well including a .357 agnum and shotgun. I'm usually a light sleeper when camping. And a semi heavy sleeper at home. Being able to wake up and start shooting to defend yourself is going to depend on several things. Some of which are how sleepy you are, how foggy your brain is when you awaken, how quiet the intruders are, if you have a dog with you that can alert you, if your door is locked and they have to use force when entering and if your door is alarmed.
This guy was asleep. We don't know if he was a heavy sleeper, had been drinking, was medicated or if those entering were very quiet or if he did react and he wasn't quick enough before they jumped him. We do know that his door was unlocked giving those intruding easier access.
I hope that if this were to ever happen to me that I would be able to react quickly and take care of the threat. But you don't really ever know ahead of time how things are going to happen. The only thing you can do is be as prepared as you can. When camping alone I would never leave the door unlocked and I will be adding an alarm of some type to to door of my TT.