“Lo sasur min hadavar asher yagidu lecha.
mishna: aseh lecha Rav. “
Actually, these references strengthen the other point of view.
The pasuk refers only to bes din. The mishnah refers to an individual, and is widely open to interpretation.
The term Daas Torah as it is used today is quite amorphous and can have so many different meanings that it effectively means nothing at all.