While I completely understand the line of thought behind this, in the specific instance of Evander Kane, I fail to see how it can be argued that the something (actual value of that something yet to be determined) gotten in return for the player, if indeed it is the case that there was no way he was coming back, is somehow not the best move right now.
The slightly better than zero percent chance that anything coming back turns into something useful surely beats out the nothing gained when he walks.
We can, of course, discuss the circumstances bringing us to this point, but JBOTs really isn’t to blame for that, by a long shot. He got what he could.