For me, I'd always allow my opponent to resign. Basically, if they don't want to play that game any more, for whatever reason, they should be allowed to resign. No good can ever come from forcing someone to continue playing if they want to go.
Basically, it is your right to resign, at any time, for any reason. If your opponent has a problem with that, it is just that, their problem. Not yours.
So I guess I don't really see this as necessary. IF you want to ask in chat if they object to you resigning, go ahead. It's a nice thing to do, but I'm against any feature that even implies that players have a duty to keep playing even when they no longer want to.