Look, you've been going on about this for 10 pages now. Is it really so difficult to understand?
Regardless of whether or not you personally think it should be a suspension, the AFL has set an extremely clear precedent. If you elect to bump a player, and that player ends up concussed, you will be suspended. You don't even need to bump them in the head. If you bump them and it results in them landing on their head and becoming concussed, you're still suspended, or at the very least asked to defend yourself at the tribunal.
The AFL has said it very clearly - you have a duty of care to your opponent and if you bump them and they get injured, you have a case to answer. Period. And they've stuck to that interpretation week in, week out for a few years now. And yet this past weekend it didn't happen, for the flimsiest of excuses: "he was going for the ball". As if the fifty players suspended for similar or lesser incidents in the last few years weren't going for the ball as well.
Further to that, the AFL has implemented a system of three fines leading to a suspension, to deal with players who are repeat offenders of minor incidents which individually aren't enough to get suspended. Cotchin was sitting on two fines. In effect, he had already wasted his benefit of the doubt. Borderline issues for which a cleanskin might get off are supposed to see him suspended now. That's precisely how the system is designed to work. And it's clear to everyone that it would have happened if this was round 15 instead of a prelim final.
Nobody is arguing about whether bumping and causing a concussion should be a suspension or not, that's a separate issue. But the problem is that the AFL has set extremely clear precedents for how the system is supposed to work, and they've done a backflip on this week purely because there is a grand final on Saturday. The rules should not change based on how important the next match is.