I can see how Vek could justify this. I mean, Kyla's body had to have been eaten by several things to get to such a state, mostly flesh flies and blow flies to start, before the beetle's could begin devouring the drier tissues. (Okay, so I've taken a few forensic classes this last semester).
So he didn't really lie to Kizz. She said "do we have Kyla's remains", and we can be very subjective. Plus, in Vek's own way he did do the "proper" thing, Kyla's bones do rest below the stones of Spellforge Keep, do they not?
Though, I'm sure he'd say that her remains lie without a grave as a testament to what destruction false pride can bring to oneself and ones friends.
-----
"By the Gods," DWARF mumbled to himself, "did I just try and justify Vek Mormont's actions? I think I need an ale..."