As to the why?
by the time Brewster left, the program was at its lowest point since the end of the Salem era. Fans were looking for someone to 'save' the program, or at least get it out of the dumps. Kill came in and was the opposite of Brewster. Kill was folksy, came off like more of a regular guy that MN fans could relate to. Also made big points of discipline and academics. he and his wife worked to help kids with epilepsy. and, after a rough 1st year, Kill brought the program back to where the team was winning 8 games and appearing in decent bowl games - by playing defense. A Gopher team playing defense. Wow!
Remember - hindsight is 20-20. When Kill was forced to leave MN due to his health, no one could have predicted that Fleck would come in here and win 11 games. There was a lot of concern about the program maintaining the level that Kill had established. Now, it's easy to say Fleck is better than Kill. But, when Kill left, we didn't know what was going to happen.
So, at that point, Kill had earned some good will. Then, he took offense to some of the comments by Coyle and Fleck. One can argue that Kill is too thin-skinned and took offense where none was intended. I still maintain that there is something below the surface between Kill and Fleck dating back to when Fleck was an assistant under Kill. I don't think this just came out of the blue.