To me, the answer to "How do we stop people from using external software to improve access to alliance banks?" is pretty clearly, "Improve the in-game access to banks so people don't have an advantage by using external software." Otherwise, you're just going encourage people to build better and better scripts to try and evade whatever limits Alex sets up to counter the previous generation of automation.
One improvement would be to let an alliance set a daily allowed withdrawal amount from the bank from users that don't have full bank access.