**Challenging the CTO on this will most likely not end well for you.** 

If you could swing another high level manager to your side on this issue they might be able to sit down and have a talk with him, but there's no universe in which you meet with the Chief _Technical_ Officer, tell him that his code is bad, and keep your job.

As for him not meeting with you .. he's not exactly a fellow developer whom you can demand updates from. Even suggesting that he owes you an update is likely to ruffle some feathers. 

You also mention that "confronting him with his mistakes" doesn't end well for you guys. Are you sure that's the best way to approach the situation? 

Wouldn't it be best if one of you guys would quietly review his code and fix it without all the brouhaha? At the end of the day he has the authority and power to say you're wrong, and you have nothing but your soapbox to stand on.

In other words, better to suffer in silence. Keep doing your job, and just accept any mistakes on his part as a reality of employment there. 

It's just one of those situations where the person who speaks up is _not_ making any friends.