"that still doesn't make tax avoidance ethical"
Obviously not, but unfortunately ethical and legal are two different things.
CEOs are not there to be ethical - they exist to "maximise shareholder value". As long as that situation is not changed, there is no amount of laws that will force a CEO to things ethically.
The only thing that can have an impact is public image. That is why is critically important to continue flaying online any company that underpays its workers, does not keep bonus promises, does not provide a safe workplace, or sources components from child labor or slave labor conditions.
We, the citizens, are the last force to make CEOs comply to what we think is ethical.
If we don't do it with our voices, the law cannot do anything about it.