I've been using this as a semi-professional title and nom de guerre since my college days in the mid-80's. As a title, it can be considered synonymous with Programmer-at-Arms from Vernor Vinge's A Deepness in the Sky. It does not mean "computer criminal."
That said, you'll never find any of my professional work signed in that or any other way. That would be dumb.
In my professional work I am a computer security researcher. This site is not about that....