Though I have never worked a day on pro hardscaping crew, I do feel qualified to chime in here. I work as a internal quality improvement consultant at a hospital. I'm a change agent with no direct power and I accomplish all my means with influence. If I can influence surgeons, I can influence joe six pack. Based on your observations, it is apparent that much of this individual self worth comes for his work. This is an ego issue. He works hard and can't stand being criticized. Its not that he has issues with you, its that when his work is viewed in a negative light, he feels threatened and devalued. He feels you are calling fault to HIM. Hence the over reaction. As much disdain as he has for constructive criticism, he probably values positive feedback even more so. Especially from a perfectionist like you. The rule of thumb in health care for coaching is 5:1 feedback. That is, praise an employee five times for every one time your "coach" them. Not all this feedback comes at the same time, and it can be little stuff (Thanks for cleaning up the job site as we went along or whatever), but it keeps staff from believing all they ever hear from management is what they are doing wrong. Additionally, the words you use can have big impact. There is a big difference between "You're not doing that right" and "Do you need a hand with that". If you believe the relationship is beyond repair, you have to weigh whether the void of his absence is less negative than his impact on daily work. I wholeheartedly believe if you try using 5:1 feedback and softer language, you will see his walls come down and he will be a more engaged and pliable employee. If he works hard now, imagine what will happen when you throw some positive feedback on his fire.