What I meant is an off the books transaction - two parties can agree to buy and sell at whatever price they wish. So the Nu peg refers to transactions which happen on specified exchanges, where buying and selling is mediating through some agreed third parties. That is a huge different to the Bitshares Peg, which takes place on their exchange (which is claimed to be decentral).
It also depends on the volume. If somebody would by 5 million US-dollars worth, the order could not be filled. The promise of an exact peg at 1.00$ is theoretically impossible. At least there has to be some spread which is larger than 0, i.e. the bid and ask will not be the same. And there is a limit to the promise of the peg in terms of outstanding liquidity.