'Twas interesting, and had a lot of great ideas, including the return to nomadic behavior, and the warrior's sacrifice.
but I didn't find it all that compelling, for a few reasons I've been able to pin down:
1. Perhaps I am too well-rooted in my meaty existence but I find it hard to really care about a bunch of space-amoebas, "human" or not.
2. The entire plot hinged on an extremely stupid leadership decision. To use the nomad analogy: The oldest member of the tribe wishes to return to the grounds of his former home, which is in the middle of a war-blasted wasteland. He tells the chief and she directs the whole tribe to follow with her without adequate resources into the wasteland which has no resources to gather, and then acts surprised when there are no resources.
-Okay, this was justified in the story by the claim that they believed zero-point energy could not be depleted. But CLEARLY it could be depleted, because prior to that point they had already talked about having to move across the cosmos to find ever-more scarce food supplies, and it mentioned that Earth was in the middle of a particularly resourceless area. If Old John wishes to go and visit his homeland, probably as some sort of dying wish, I can totally respect that. But the chief dragging the whole tribe along with him to certain death is just disregarding the value of all of their lives, all for a trip of nostalgia that only holds meaning for one person, no matter how venerable and respected he is.
3. The happiness of the plot depended on a series of deus ex machinas suddenly popping out of nowhere and saving the day, until those moments things looked hopeless, again, until John finally speaks up. The resolutions were just too convenient for my taste, by all likelihood they should've starved or been torn apart by the wolves because of their terrible decisions, and they only survived because of conveniently placed solutions.
-By searching the whole area, they come up with exactly one puddle of energy. If there was one, why wouldn't there be more? And if they hadn't found this single one, if their search had gone just a little bit to one side of it, then they would've all died. If there was so little energy left, it's just luck that kept the wolves from eating the last of it already.
-They're up against the wolves, losing, getting torn apart, at which point John suddenly reveals that he's a super-weapon more than equipped to deal with these beasts. Phew!
-They're stuck with no further resources, and many wounded, and then John, again, conveniently steps in to save the day. "Oh, by the way, the humans back in the day kept energy caches nearby." Oh, thanks for letting us know that before, Johnny.
Perhaps this string of deus ex machinae speaks of a more sinister motivation on the part of Old John! Consider this:
Old John is tired of being disrespected, and being a drain on his tribe, so he concocts a scheme that will allow him to die in a blaze of glory while saving the lives of the rest. He knows the chief well enough that he can con her into dragging everyone else along, and he knows where the bomb cache is hidden. His plan is to drag everyone there until they're starving to the point of desperation, then pull off his bomb trick to save the tribe with his sacrifice. The bomb's probably not even broken and in need of his direct intervention--it's all a ploy to necessitate his sacrifce. It's not like any of the others know how bombs work--they've got to take his word on it. The plan is all going smoothly until the puddle of energy is discovered. "Damnit!" he thinks, "What are the odds?!" So he has to improvise. He knows well enough that if energy is that scarce there will be wolves, so he adds a new stage to his plan: watch while the wolves slice and dice, but step in before the losses become too grievous and show off his mad warrior skillz. His improvisations work splendidly and he succeeds in his mission, and no one is ever the wiser that they were all pawns in his scheme to immortalize himself.