I like to stretch my students and if we can use new joints and various construction techniques then all the better. No metal is used in this shave horse. The table is held onto the bench by oak dowels. The legs are the sliding tapered dovetail joint, one of the best green wood joints of all time. For easy knock down these legs will tap out with a light hammer blow even when wet. Try doing that with a round mortice and tenon joint. The wood is green so this type of joint will still work after warping and drying.
The shave horse has 3 leg the one at the front will act like a wedge in the bench forcing a split down the length of it. To overcome this Ben carved a special joint in the rear table support, so no matter how the leg acts as a wedge the wood will not split.
If you want to see another bench made using the sliding tapered dovetail method have a look at this post: http://seanhellman.blogspot.co.uk/2010/11/tapered-sliding-dovetail-bench.html
and this one for green wood: http://seanhellman.blogspot.co.uk/2010/04/tapered-sliding-dovetail-joint-tree.html