Yes, that's what I basically had on mind (not this specific tool maybe, but methods based on precomputed tables).
Regarding the detection... well, that's the problem with the [Tool] stuff. I think you'll agree that most ordinary users won't have this program on their computer (meaning that if they have, somebody has probably put it there without their knowledge). That's why it's detected right now... hopefully it will be possible in the (near?) future to configure avast! to detect / not detect specific types of files (such as [Tool], [Adware], ...) just as you wish.