Wow, this guy is dead serious!
... and the other guy is seriously dead.
Frankly, I don’t care how studly a guy may believe himself to be he should not have gone in alone. Even saying the other guy was there to help move furniture rather than for security makes sense of them being there.
Going in alone was one of the landlord’s first mistakes.
The best course of action would have been to just CHANGE THE LOCKS and worry about getting their stuff out later.