It’s obvious, that this problem is caused by the chosen oracle design as liquidators can post the new prices themselves. Instead of trying to cure the symptoms, I think it’s a better idea to cure the problem at the root. This means by replacing the current oracle by a better solution. This can easily be done by using an existing, proven solution like Chainlink.
The oracle solution, which is discussed here, won’t solve this problem as it can be read in the protocol of the last developer call: “Getty mentioned that posting is somewhat subsidized by liquidators because it is in their best interest to post prices on chain in order to perform liquidations. In the early form of the Medianizer there will not be any new considerations to gas costs.”.