The average thief is not going to be recognized as Notable, and as such, wouldn't receive the template. However, I do get your meaning. If one of these individuals made a successful habit of thieving (a modern day Robin Hood, for example), then they could be labelled as such.
However, bringing this back to the spies and traitors - I get that the dictionary primary definition tends to be not very flattering (however, there are secondary definitions that could apply), and since there are always going to be two sides (winners and losers) in the spy game, someone will always see them as hero and others as the villain.
Either way, as mentioned below, I'm not opposed to separating them, but there are challenges with Military and War (not all spies are military, nor do they operate within the precepts of a war) and if keeping them within Black Sheep is not acceptable, then they almost would have to fit within their own subproject somewhere or possibly have no project at all (other than Notables, which would still be fine with me).