We don't have any APNGs on the site, but we do have some animated GIFs.
There's no real "policy" on animated GIFs and APNGs. I'd like to think that I rarely reject files. In any case where I might have reason to be critical, it would be a case-by-case basis. It's really more like what's common sense, what's wieldy/unwieldy, that sort of thing.
I agree that the Lavos Core segment would look impressive if animated. Don't think it's required, just cool-looking. However, (and I'm not familiar with how the animation in APNGs work) if the animation requires the entire image to be repeated per animation frame, it could balloon the filesize up. Sure, it's only 92.8 kB to start with, and if there's only a few frames, it might be okay. If it became 10 MB (which it surely wouldn't, but I'm just saying), then it might be a questionable choice. Animation is more often a "neat" (as in cool) thing than a necessary one.
TerraEsperZ's animation of the penultimate stage of
Battletoads, "The Revolution", is rather cool because it's difficult to show how the stage is otherwise (other than static front/rear views - though he provided those too). And it looks awesome and is therefore worth the 4.68 MB. Though we also have ugly maps that are bigger so why should I judge?
There's more than just size to consider though. I recall Revned (correct me if I'm wrong) once tried making animated Mega Man III stages. They looked cool, but I seem to recall the concern then was that browsers don't all display motion/animated PNGs the same way. If they can't display the animation and only show some frame by default (whether it's the first or otherwise), will that still be a good map?
Kind of ironic that I'm talking about unwieldy filesizes and inconsistencies across browsers when I know those are the two problems with the static HTML listings on this site... >_>