DISC as coaching tool

Just got off a coaching call with a wage roll employee that his company values him enough to pay for the service. He was the most outspoken, arrogant, untrusting person in the plant. Every meeting with management, he did everything possible to disrupt the meeting and question the leadership in public. His decision was essentially learn how to play with others or you can look for a new job after 18 years with the company. When we got the results from his DISC, it was obvious. The employee was driving, ambitious, pessimistic, impatient and exacting. We did a 360 with his peers and he ranked lowest in accepts feedback and role model for others.
Why did his supervisor put up with this? He was the most technically competent operator in the plant. He just had no patience with others? Couldn’t tolerate their slowness and did it himself.
We did not want to lose him. What kind of leadership coaching could we give him that would work?  We sat down and reviewed his DISC and 360 feedback and told him if he wanted to be considered for a senior operator job, he had to work with people. We explained how to communicate with different styles of people and how to recognize them. Within a week, he asked others opinion. At first they just stared at him. Now they believe he is sincere and are helping him work on a project to make their job easier.
Without the DISC tools as coaching data, we could not have salvaged this valuable employee.  He has recently been awarded the site senior operator job!  He has gone from one foot out the door to our most valuable leader on that shift.