You are right of course, and there is no doubt it should not be tolerated and he did do this as a professional earning more than the majority of people who graft every day.
I suppose the but is this. Managers are paid to manage players and personalities. O'Donnell, Tierney & McKinstry aren't playing just now and it'll be up to Kettlewell to motivate these guys too. Hammell didn't manage Van Veen and what he is. He wants to win, and get goals. The manager did not give him the support he required by his formation.
I won't dance on his grave but he mismanaged him & a vast number of other matters.