The military evolution explanation of the Bronze Age Collapse does not explain the motives or origins of the invaders. If widespread piracy was a factor, there must have been some cause.
If the Sea People really had learned to use superior technology to fight the established elites of the Bronze Age, it begs the question of why a disorganized band of pirates and raiders hit upon the idea before complex civilizations did.
The Sardana or Sherden, are mentioned many times in Egyptian texts before the Sea People invasions, and appear to have been used as Egyptian mercenaries. It is unlikely the Egyptians were surprised by their use of swords and shields.
The military invention explanation does not sufficiently explain the origins of the Sea People.