Whilst I realise that it is nigh on impossible to achieve absolutely 0 degrees AOA we must come close to it at some point during level flight - why then doesn't the near zero lift cause the plane to porpoise in flight?
There is sort of a natural "anti-porpoise" that comes from the cg being appreciably ahead of the neutral point of the airplane. Pitch stability comes from the horizontal stab/elevator being adequately large and adequately far enough aft to "stabilize" the pitch. And that's what it does.