Calling them "Greeks" is more than a bit incorrect and a kind of back-porting of the concept of Hellenism into a very pre-Hellenic time. Even if it's true that the Sea Peoples were Mycenaeans or Achaeans, they did not call themselves "Hellenes" nor have anything like the sense of a Hellenic identity that developed much later in the iron age.

I think of these people as groupings of war chieftans and landholding warrior aristocracies and their crews, conducting raids abroad and territory at home, similar to the crews of Viking ships. Similar in that they had skill with ships, and similar in holding onto older Indo-European traditions of raiding (back to Yamnayan cattle raids on the Pontic steppe), class structures (warrior/priest/farmer) and systems of managing subjects and fiefdoms.

Calling them "Greeks" is about as accurate as calling the old Vikings "Norwegians" or "Swedish". Related by descent, but not nearly the same, and almost 1000 years separating them.