That's what I thought at first, too, but we ended up on a train after we died, and that's what took us home. Dying was the only way to board it.

[...]

Percy-san ended up dying, too, at the very end. After he used what he got for winning to make sure we'd all be taken back. That's a choice only the winner got to make, so a lot of people ended up working together to make sure it was him.

[i'll say it here too instead of just in dms: the honorifics kill me, but i'm in the middle of a reread and it feels wrong not to have sei using honorifics because she's such a stickler for them in canon.]