In general it is impossible when deleting a zone to know the full consequences of that action unless you are that zones DNS administrator, and even then you need to ask any administrators of delegated domains.
Not just deleting.
So those who think deleting zones is a way to fix things, or penalise people, should tread VERY carefully, less they end up liable for something bigger than they expected (or could possibly imagine).
There was a case not long ago where someone decided that it was a good idea to change the NS records in lame domains. This caused a major service outage for a company who needed this specific domain to be lame in order for a certain service to function. Fortunately, we were able to find the domain technical contact who was able to log into the registrar and put the lame delegation back. Now, the problem has been solved by moving the domain to another registrar whose goal is to keep things the way they are, not clean up lame domains or other perceived errors. --Michael Dillon