That’s a really great blog post. You have new formulae for duals, you explain the duality of the 2 norms, you have a new composite norm that is always a dual number (instead of only sometimes), you have cool anti-projections onto lower dimensional spaces, the list goes on.
No-one will ever change the fact that the native geometric product of G(3,0,1) motors vectors around like planes. I understand holding to that. But your results show that the anti-operators of a Geometric Algebra belong to it, whether one works in the direct or dual basis. I agree that to not include them disrespects the symmetry of the set of basis blades, obscures structure, limits insight and complicates computation, particularly in the projective case.