First time I disagree with you. Yes, there are great reasons to do this, and I get your point for voting rights.
I even think that we should remove voting rights from the accounts that belong to exchanges.
The problem is not about voting rights, but about not allowing Justin to powerdown/sell his stake. It's just flat wrong. He bought it, and it's an investment. The whole point is to make a profit.
Saying the stake should be used for Steem's development is the most naïve thing ever. Even if it was a promise with Ned, the promise was broken when he sold the stake.
The way I see it is that Justin will spend his own money to improve Steem to get a good ROI on his stake, not use the stake to improve Steem for no benefit at all.
Now Justin owns it and he 100% should be able to powerdown. Even if it fucks up the plan for the negotiation, so be it, we fork.