I know you Dave, you're an honest man...when you say that the cue is in perfect condition, I 100% believe you.
On the other hand, I don't know the other party, but him going quite does not mean he's guilty, "Hear me out on this one cause I had a similar situation in the past".
There's a good high chance which I feel may have happened that both of you are on the right, you'd be asking me now how is this possible? Let's rewind from the beginning.
You sent him a cue that he desires for $1000, in perfect condition, like new. And he expects it to be as such;
The cue gets shipped and along the way it gets hammered during the delivery, gets damaged, severley damaged. Then it arrives to its destination, the guy opens it up and see's that its hella damaged, he thinks you've sent him a damaged cue.
Now he ships it back and requests a refund, then you think he damaged the cue.
Neither of you is in the wrong if this story above is true, but he gets his money back and doesn't care much about you cause he thinks that you've sent him a damaged cue. The most important thing to him is his money; he ignores you.
Believe me Dave, I did not read all the comments above but I got a feeling that this is what I have told might of actually happened. These shipping companies screw up stuff all the time, even if you've packaged it 100% securly, they can screw it up trust me.