Yes, that's why I want to elevate mine as well, let's say if a pipe breaks when you're on vacation. I have not only the sump pump, but a large boiler drain that I could rely on if the water gets about a half-inch deep. We're going to have ceramic floor down there so in the grand scheme of things we'd have a couple wet carpets and some drywall/paint to do.
I think the carpet is a good idea as well, just as long as the anchors poke through it.
Until it does get wet, however... then it may get moldy and it would be a real pain to remove...
I just did some precursory research on hardiebacker's compressive strength (the cement-style drywall you use for inside showers and such) and it's saying it's at 7,000 PSI compressive strength. I think weight of safe + torque from anchors won't get near that, so that may be a good option. It's easy to work with, and if you're concerned about rust you could Dremel an airflow channel or something on the surfaces.