That looks like nothing more than a rotten radome collapsing in flight.
And since NWA farmed out most all of its maintenance I can beleive that that is the case.
Could some sort of sudden change in pressure do this? If it were a bird or another object I think you would either have a mark from that object or some paint taken off the nosecone. I am guessing a dented nosecone doesn’t effect the handling of an aircraft all that much?