If you compare the Hogan swing from earlier in the year for which he got off, and the Heeney swing, then Heeney is a bit unlucky (or Hogan was a bit lucky).
Both were guys lashing out towards a player's head: Heeney's had more to do with the actual play, but he had the bad luck of giving someone a blood nose whereas Hogan more-or-less missed when he actually tried to hit the Carlton bloke.
The AFL has been pretty clear that they focus on the consequence of the action in handing out suspensions, so I reckon once blood started coming from the nose of bloke Heeney hit Heeney was cooked.
I reckon the Tribunal should now get to categorise offences as to whether they make you ineligible for the Brownlow. I get that the 'fairest' part of 'fairest and best' should stay for an umpires award, but the bit they were trying to discourage was behind the play hits. If the Tribunal is mostly concerned with the consequence rather than intent, and you can get suspended for things bordering on skill / technique errors, then perhaps the Tribunal should weigh in on intent for Brownlow purposes.
If I were the Tribunal in this case, I would have given Heeney one week, but kept Heeney eligible.
I wonder if you had that system in place for Cripps whether he would have been suspended last year? I reckon they might have ended up giving him a week but saying it was careless and therefore he was still eligible for the Brownlow. I think that's better than the Tribunal / Appeals team twisting themselves in knots get a Brownlow favourite off.