Bitcoin cannot turn into a stablecoin because of it's scarcity. This leads to unstable price and increased volatility. A stablecoin must have way lower scarcity. Maybe this guy from Twitter wants a stablecoin, that is backed with gold or oil(but the price with volatility remains).
There simply isn't a financial asset or a commodity, that has perfect price stability. Even gold doesn't have a perfectly stable price.
Making Bitcoin a unit of account(or standard measurement) won't change anything. Bitcoin will remain as volatile as it used to be. Declaring Bitcoin a unit of account won't miraculously make the BTC price stable and cause Bitcoin's volatility to disappear.
Also, dreaming about a non-KYC stablecoin is delusional, if you ask me. KYC is here to stay and the governments would become even more aggressive when imposing KYC policies.