I think you got it backwards. For your AI to succeed, it needs to poke a hole on all layers, not one in many layers. If an attacker pokes a hole in n-1 layers but the 1 layer remains untouched, the system's integrity is preserved.
Why do you think defense in depth is a basic concept?
Defense in depth says that simply compromising your application code shouldn't provide access to the physical hardware you're running on, and that's hopefully the case, but it doesn't mean your app is not hacked. It just hopefully means that a hack on your app code doesn't automatically give the attacker access to your entire company.
That's really not how it works. You reach the compromise part if all layers are compromised. You don't reach the inner layers if you can't go past an outer layer. You're saying that if there is only one layer that is compromised, or all layers are compromised, your app can be compromised. But you're leaving out when you can't go through every single layer. That's the whole premise of defense in depth.