I'm not convinced it's necessary. It's an obvious suggestion to make because it's used so frequently in stealth-em-up games to the point that it's sort of a trope now. Honestly, the number of times I've actually found this feature useful in games that allow it (two most recent titles I've played being CP2077 and Far Cry 5) is a short list. And actually, the number of times I've seen another NPC find a body in Odyssey is so low. It does happen but it is eminently avoidable by just not killing your target in the wrong location (or just killing the second target that shares the same space). You'd actually have to force its use, like CP2077 does, to make it worth developing (and CP2077 is a game that literally places enough "bins and lockers" for you to conveniently shove your victims into, at every location - it's very much a contrived mechanic in my opinion).
In terms of what I think the stealth game needs, I'd put this quite a long way down the list. Just my opinion, of course. But I've spent so much time doing stealth that I think I've got a pretty good idea of how useful or useless certain features would be and I think this feature errs on the side of gimick rather than game-changing. I think much more useful would be the ability to distract or divert, to redirect an NPC away from a location. The stealth game currently is mostly about patiently waiting for NPCs to move to a suitable location for us to do something and it's great fun but it'd be fantastic if we could use discretion and skill to direct them, with care. I think I'd also like to be able to simply knock a target out, rather than only be able to kill them and I don't think we should be fined for that at all, it should just be much more risky to pull off.
Beyond that, I'd much prefer Fdev work on creating new scenarios for us to work out (like prison breaks, being a really obvious missed opportunity at this stage). I think the "stuff we can do" in stealth is pretty well fleshed out right now. Certainly way more so than any game loop in Horizons.