Penumbra (Requiem) Ending General Discussion

[JKO]

But a friend with the power to "kill them all" would probably have a boat that is higher in caliber than the small fishing boat on which he arrived.

Maybe that friend decided to be the best of humanity (he he, Doctor Who), what Philip couldn't be, and extracted him quickly and silently from this place, leaving the Tuurngait forever behind, as they are the only 2 who still knows about it. Don't forget that the Tuurngait is "happy" when you learn from your mistake during its challenge. Maybe it offered him one last ultimate chance.

And throughout both games, Philip constantly foreshadowed his own death. "The last time I would see civilisation", "the last flight I would ever take"

This can simply be a symbolic representation of his life. It happens a lot in movies and stories: his old self as died. The one who wanted so much revenge for his father is dead, leaving only the "new" Philip. The Silent Hill-ish boat could be the remnant of his old self, a bit like Clarence (or whatever is his name) said in that room: "No order without chaos". He won't have his new self without the chaos of the old one, he is marked from it, but he decided to move on and not to die with his guilt about Red.