I'm sad that you think so. I would never stiff a client or customer (I'm a designer) and have friends who have gone unpaid so I know how distressing this is. I also abhor the idea of not paying people who work for me; I've never done that, and never would, even if unhappy with the work produced. I have stopped working for a client in the past because I found they didn't pay tradesmen working for them, so this is an important principle to me - if someone does work they deserve to be paid for it.

I just think this is absolutely the wrong response. As a freelancer or business your reputation is paramount - that reputation should be for professionalism and courtesy, even when others are not professional with you. This sort of incident teaches us the value of contracts, staged payments, and trust with your clients. If you don't have a good trusting relationship with clients, it's best to end that relationship and find other clients. If a client screws you, I think the best response is to make sure people know what they did, and adjust your process so that future clients can't do that, not abuse your power over their domain/server to post a partisan message like this.

So I'm afraid your assumptions about my motivations are completely unfounded - perhaps you'd like to rethink them and offer me an apology?