...they just live off the AFL indirectly (ie. by being gifted a commercially lucrative fixture).
I'm pretty sure the Cats forced the issue on Ablett and got more than they would have done if they'd kept Mum.
In fact, the 'flexibile' approach of the AFL when it comes to their policies is apparent in your next point:
Why shouldn't it have happened? There was a marketing allowance - working in a similar way to the salary cap - available for all Clubs to utilise, should they be able to find companies willing to tip in, of course. This doesn't seem any more unfair than having Clubs allowed to pay '100%' of the salary cap while others pay in the low 90s, and some might argue that it isn't significantly different to the fact that some Clubs can pour so much more money into their football department and facilities.
I think there are two problems with the AFL's change of heart.
First, the fact that the AFL decreed that the marketing cap could not be used to retain players just as GWS and GC start pillaging lists means that while some Clubs have players on their list that are benefiting from these arrangements, other Clubs cannot use them.
Second, iIf the AFL did indeed want to put an end to this marketing allowance, or at least modify it, it seems to be that the fair way to go about doing so would be to phase it out/modify it at the point any existing arrangements expire, so that all Clubs would be on an equal footing.