The intent was to cheat the tests by secretly tailoring the behavior to the tests, even though they knew that real-world driving would be different and that the tests are supposed to indicate real-world emissions.

Intent matters. You can’t set out to cheat a test, succeed, and then say that it’s legal because you succeeded, any more than you can steal from a store by hiding an item under your coat and then say that it’s legal because you disguised it well enough to fool the guard.