I'm going to leave this thread open for a little longer, in case anyone else has any input on this.
But just to clarify that if you are seeing someone who is trying to find a way round the contact information rules with spam posting, report them! We do see a lot of infractions on our rounds but the community's input and alerts are key to keeping BHW running as smoothly as it does.
Furthermore, currently we have no plans to disallow contact information in signatures. We regularly review our rules and policies, so if that situation changes then we will let you know.