I actually agree, in the same way that selling lock picks or guns is ethical. They are just tools. How they are used is the responsibility of the person wielding them.
I can think of benign uses for lock picks and guns. What is the benign use of a secret exploit?
it doesnt have to be secret. for example unlocking old phones. There are certainly people waiting for the right exploits to get access to their old wallet.
One example I can think of is the WoW private server Warmane uses an RCE to extend client functionality.