I don't imagine that Glenn even considered ousting Don H from the band. When Glenn decided to leave he called Don & told him. I have read ( wish I could remember where) that Don had wanted & ecpected that the band would continue for a while longer & had a hard time psychologically & emotionally when they disbanded. Timothy states in the HotE that he called Glenn to ask if it was really over & Glenn told him that it was. Timothy then says that he had been in the band for less than 3 years & he loved it. It was his dream come true. Joe has also stated that he loved being in the Eagles.
It's interesting that once Glenn said that he was quitting the band the others didn't seem to consider that the Eagles would carry on without him. They seem to have come to a screeching halt. At least, I have never seen or heard that they did. Please correct me if anyone has heard otherwise. Don H has said that in retrospect it was the right thing to happen, but he certainly didn't think so at the time.