In my thought, locking up the coin price in a fixed price will be the same as killing that coins, many people will be leaving that coin behind, because they can't trade that coins to generate profit from that respected coins. It will surely able to be used as a payment tool only.
If there is a similar conspiracy of the exchanges, people simply will not use them and will look for other ways for free trade. And such opportunities will always exist. No administrative pressure can affect the free price on the market, which will always be formed on the basis of supply and demand.
In general, the establishment of stable prices in the market is impossible. This is contrary to the principles and spirit of the market itself and the exchange will never support such an offer.