If that's the case... he should of been let go even more so.
The fact that someone raises or threatens to raise a grievance isn’t by itself proof that their complaint is justified.
If (and we only have rumours to go on) multiple staff felt the need to go down that path then there was obviously unhappiness in the camp; but unless the club had already investigated all the facts, then like everyone else in this country Chiefy is presumed innocent until proven guilty.
Edit: If people were paid out (again, rumour) then sure, it makes it more plausible the club was heading off what it could see was going to be a train-wreck. But these processes take time to resolve and in a small organisation they impact other staff, so perhaps they just wanted to avoid the distraction regardless of the outcome.