The thing that's infuriating about Jason's death is that it was squandered, used for shock value, and done outside his story arc.
Jason should have died in BoO and looking back there's such a good way to do it that's in character for everyone and so heartbreaking. So go on this angst trip with me will you?
Jason and Piper don't actually get together after TLH and instead you play out the Will They or Won't They thing. You keep Jason disguised as an old man going up that hill, but the whole time Jason thinks about how he'll never get this, how he'll never get to grow old, he's too much of a soldier, too valuable to the gods to die peacefully in his sleep. You also keep Jason imagining himself as an old man with Piper, but you soak that daydream in the convoluted fuzziness of something you know you can't have. Jason spends the fight with the giants imagining something he so desperately wants but in his gut knows he can't have.
And you change nothing about Leo having the physicians cure btw. So here you have two kids, each of them told that they have to be the one to stop Gaea, each of them planning on dying to do so, and neither of them sharing this. So the soldier marches into the fight ready to hold the line, while the engineer tries to leverage every loophole he can. And we get to know this is happening. We watch the two of them head down these paths and can do nothing about it.
When the final fight comes Jason throws himself into the melee with every intention of making the final blow but he can't. He realizes he's not enough, but Leo's plan will work, it will sacrifice the Argo and whoever is flying it, but it will work.
So Jason gets aboard with Leo, he clears the way for his friend to save the world and at the last second throws Leo clear of the ship, telling Leo to find Calypso, and to tell Piper he wishes they could have built something real.
And in the end everyone has lost. Leo pulls the broken vile of physicians cure from the wreckage knowing if he hadn't kept things in... Piper has to bury her friend and realize not having been with him for real doesn't make the hurt any less painful... Frank realizes sometimes your heroes and idols are mortal, fallible, expendable... Hazel sees that nothing ultimately has changed, gods exchange the lives of those they ruin as easily as coin... Annabeth watches someone who has faced a life so similar to her own be consumed by it, never having the chance to break free, to have a future... And Percy, oh Percy sees that being claimed ultimately means nothing does it, not when at the end of the day you bleed and the gods live on...