This is one natural event (I don't consider it a "natural disaster" because it is just doing what a known active volcano will do) where no one needs to get hurt, no one needs to get stuck, and most people can get their most valuable possessions not affixed to the property out, as long as they act in a timely manner.

I am reminded of whenever there might be an earthquake in LA that well-meaning people might check up to see if I'm ok. Accordingly, if you're headed toward KOA, absent some catastrophic explosion which results in an ash cloud that pollutes the airspace, I wouldn't cancel.