As is often the case there are two sides to everything and right & wrong on both sides as I expect is the case here. However what puzzles me is that the rider stayed in contact with the club during his injury lay off and never raised a grievance despite having multiple opportunities to do so which is very odd.
He obviously no longer wanted to ride for King's Lynn and wanted to be elsewhere. There is a narrative that Lynn are a shambles but plenty of experienced, quality riders are happy to ride for the club and return after leaving so it's obviously not the case. Sometimes people just don't click with eachother and can be on different pages, I suspect that is what happened here.