Is NMS a stable coin?

Nope. NMS is not a stablecoin.
Rather, NMS aspires to become an algorithmic reserve currency backed by other decentralized assets. Similar to the idea of the gold standard, NMS provides free floating value its users can always fall back on, simply because of the fractional treasury reserves NMS draws its intrinsic value from. In terms of a reserve currency, NMS is far better suited to the task than stablecoins pegged to USD.