The Duchess
Wise Old Thumper
If it was me, I would just bluntly asnwer "You want rid of the rabbit, do you?"
It's very hard not to say that..............but ultimately if you want them to do the right thing by the rabbit, it's important not to pee them off until the rabbit is safe.
I am usually quite patient while people tell me their stories. I wonder if they can tell by my normal lack of 'empathising' in many cases that I simply don't buy their excuses very often. So many people think that you've maybe not heard their reason before, despite it being unusual. In fact even those who have 'normal' excuses like the kids got bored are sometimes terribly surprised when you tell them that it's common and that you are full becuase of such reasons. Some people just have no clue just how many rabbits are given up - that's the reality of it.
I am fairly blunt but try not to antagonise by speaking my mind until I know I have the rabbit safe, or if I have no chance of helping, I make sure they understand exactly what the must humane and reasonable way to otherwise rehome would be. In other words, lay on the guilt, directly but gently.