I had sent a ticket in to CS about this, just to get their take on it. I did not speak to a GM as I wasn't online when they replied, but this is what they wrote:

Answer: It could be considered a violation of policy to advertise that website so I would not advise it. However, you could refer them to the world of warcraft policies page http://www.worldofwarcraft.com/policy/.

Soo, now I'm confused. This is what I was afraid of, advertising a website and getting banned because of it. However, you multiboxers who have been playing for a long time have always referred them to these websites and have not been banned yet, but I still don't like the GMs response. How else am I supposed to inform someone that I am not "cheating" or a "bot" if I cannot tell them about these websites?

I just sent in a ticket with the following:

I sent in a ticket about this earlier, but I am confused about the answer I got. A repeat -- I am a multiboxer, and occasionally I get called a "cheater" or a "bot" -- I want to inform these people, as I am not either of them. I asked if I could inform them by having them go to dual-boxing.com and the answer was "it could be considered a violation of policy to advertise that website, refer them to the world of warcraft policies page." How is that website against policy when dual-boxing is legal?

I would have written more and explained it better, but they limit how much you write in that box.