This is way too much of an over simplification of the situation because you talk about it like it was one event when it was multiple.Initially I thought they were raiders like many other people, but more recent evidence and better translations suggest that they were rebels. They were a bunch of minorities who had lived in the region for centuries and periodically attempted to shake off the rule of the Pharoah. The recorded "Sea People" attack wasn't the first nor the last of these rebellions. It has been fixated upon by some historians in an attempt to rationalise their "collapse" theory.
There was no Collapse. There was no Dark Age. It only looks like one because of the dodgy chronology we've been saddled with.
The Egyptians recorded 9 tribes of Sea Peoples, not 1, whether this was due to a "collapse" etc is not my concern or what I'm trying to prove, its you who seem fixated on that theory.
The 2 which have been afforded the most attention seem to be the Sherden and Peleset.
The Sherden after their defeat by the Egyptians had some prisoners incorporated into the Egyptian Army by Ramses II, who of which were used in the battle of Kadesh against the Hittites, this is recorded on the Aswan Stele and the Medinet Habu.
Now its possible that after one of these attempted raids were defeated the Egyptians did allow a small encampment or village of Sea Peoples to settle in exchange for mercenary service but again this would only address one occasion and was not long term.
The facts that have been unearthed clearly show that all Sea Peoples (I mean the name says it all) originally came as foreign naval raiders and were SE European due to DNA, then add the weaponry, clothing, armour, pottery the answer becomes relatively clear.
There is no reason in my mind to think this description isn't perfectly valid ..........