There are many connections between low NSR price and low buy support on the peg. You can certainly see how parking benefits the buy side of the peg, yes?
Connection 1) Custodial support is connected to shareholder wealth. If shareholders are strapped for cash because they are buying NSR at low prices, they will not have funds to contribute to custodial support. If we need more buy side liquidity, custodians will not have funds to buy NSR at low prices.
Connection 2) Reputation and public perspective. If the peg breaks down, NSR plummets, this much should be clear. Inversely, if NSR is high people will buy NBT because they perceive Nu to be successful.
Connection 3) Burning. This is a direct connection.
Regardless of if we use connection 3 or not, we cannot ignore NSR price because of connections 1 and 2.