There's a difference between talking about the law and "legal advice." I have an ethical obligation to avoid giving anyone a sense that I am forming an attorney-client relationship with them by giving them legal advice. The signature is a snarky way of making it clear that, while I might be talking about the law, I am not giving anyone any legal advice in any sense that should be relied upon.
As for my client pool, my client is the largest employer in the country, so I'm not exactly looking to build a private practice. My goal in coming here is to talk nerdery, being a geek who dual-classed into law.
Mathemeticians stand on each other's shoulders while computer scientists stand on each other's toes. -- Richard Hamming