One of the points of the post is that if you reject axiom 5 you are left with something that strongly resembles the natural numbers

That doesn't work. If you reject induction, your remaining four axioms also describes the set {(n,m) such that n and m are natural numbers}, where (0, 0) is the zero element and the successor of (n, m) is (n, m + 1). That seems a bit different than the natural numbers, because I added, without violating the first four axioms, additional elements that are not the successor of any element.