Not as long as they own a lot of the coin itself, no. If any of these miners sells their stake, freak out immediately since their next step would be to short bitcoin through some means before causing a value crash. And you’ve also got to consider market reactions; if any of the miners sells a decent amount of their stake, freak out immediately- because they’re liable to sell more soon, causing everyone to freak out and crashing the market. And so on. This doesn’t sound stable- perhaps the whole thing could be taken down by a miner deciding he needs a bit of cash to buy a house.