You're absolutely right. It doesn't necessarily follow, and I'll admit this readily since after having read a number your posts here on CF you don't seem to strike me as a Hedonist. But I thought I'd go for the low-hanging fruit first. ...
And what if we view this ephemeral 'good' differently? Well, it's always possible that we could, but then I'd have to get down to brass tacks and ask: how ephemeral is the presence of trophic levels in nature, Bradskii, if we were to take them as but one 'ephemeral' example?
I guess if I were a more rigid Hindu, I might possibly think one thing about the presence of trophic levels in our world, but as a Secular Realist I could very well think another. (...and Bradskii, before we go to lunch, may I ask you how you like your steak?)
I'd say that their presence, as painful as it can be for us to realize their inherent existence as we engage them on a human level, shows evidence of a 'good' that is difficult to put into axiological terms other than express attributes of biological function. Their existence beats the alternative, even though, ironically, their existence almost seems to involve the alternative [
DEATH!!!], but not exactly in the same way as we find the alternative elsewhere in our world in relation to overall Entropy.
Of course, it might become even more ephemeral for us if we attempt to find agreement in the valuations we'll make between us when we're faced with a Caesar Salad rather than a juicy steak...