well.
you do not get penalized if you stop selling players.
The thing bothering you is that the players you bought to be able to sell them with profit (as you where doing before) are not sellable with profit at this time, which is exactly what was intended, and announced. I can't see how you think you are penalized...
You say so yourself, if you keep doing what you did (which is what you do if you sell those players) you may get penalized. If you do not do what you where doing anymore (by not selling those players) you are not penalized.
Now tell me how you get penalized? You did not have to pay any fee on your previous sales I hope?
Ofcourse this new rule kicks in for each manager with a defferent impact, and I believe you can understand that there is no other way.
How would you suggest BB should have implemented it to be equally fair for all managers?
They are not your friends; they dispise you. I am the only one you can count on. Trust me.