That tool was a complete mystery to me, too. There have been a lot of specialized turning tools and gadgets that have come and gone over the past few decades. Most don't live up to the sales pitch, and fade into oblivion. Somewhere, I still have a gouge with a really strange grind on it.....If I remember right, it has a normal looking grind on one side, but the other side was sharpened about half the distance to the end of the flute. I don't remember who it was offhand, but it was some semi-popular turner's "signature" gouge. I never did see what that one could do that regular 'ol traditional tools couldn't do.........
Live and learn!
ko