I agree totally and don't have a specific proposal for addressed mined STEEM, except that we probably shouldn't encumber or interfere with it until there's a hard fork resulting in two chains going forward.
If an entity like Tron or the exchanges decides to hardfork and therefore create two chains, I think it's more justifiable to punish them and their tokens on the legacy chain.
How do you propose that stake originally not produced via the rewards mechanisms be separated from Steem created through the rewards pool?
Freezing or seizing the STEEM / vests from certain accounts that ninja-mined comes to mind. It's a sub-optimal solution because if someone ninjamined and then transferred prior to this, they'd keep the STEEM. Again, I don't really favor seizing other entitity's assets unless they continually demonstrate that they are using the assets to threaten the survival of the network.
I note that freezing the stake of Tron is exactly what witnesses attempted to do, and failed.
We no longer have that ability, and unless Tron and the exchanges execute code voluntarily to prevent their governance of Steem, the blockchain remains the exclusive possession of Tron.
The ball's in Tron's court. We await their pleasure.