Maltz has had a couple of fates iirc but the one from The Genesis Wave is my favourite one, that he survives a century with the shame of being bested by Admiral Kirk, helped Dr. Brahms when the Genesis wave was unleashed, and met with an aged Carol Marcus, holding her in his arms as she died.

Something I just remembered from the novelization too (that I haven’t read probably since I was 14) was that after Uhura helps her comrades to the ship, Mr. Adventure is still protesting from the closet that he wants to help but she doesn’t want to risk his potential career. The she basically flees to the Vulcan Embassy, with Starfleet Security hot on her tail.

Everything works so achingly perfect when the Enterprise gets to Genesis, Kirk pulls one over the Klingons, gets spanked for it, David is killed and just rips the fresh wounds Kirk had in his heart again. And Kirk has one last card to play, and it’s a doozy.