Doesn't seem self consistent. He defines the ab multiplication as dot product plus "extrusion"/bivector (which seems simpler to call convex combinations of 0,a,

Doesn't seem self consistent. He defines the ab multiplication as dot product plus "extrusion"/bivector (which seems simpler to call convex combinations of 0,a,b,a+b). Then he says aa is a scalar, presumably because the "extrusion" is 0, but you can't have this identity be 0. Just because it's degenerate does not mean it's 0. And the "extrusion" while not a plane is a line in his definition.