What does "watch your arguments" even mean? It's just "Dont say anything I disagree with" with a threatening tone.
For many humans "watch your arguments" carries the same tone as "pay attention to those boxes you're standing on".
A reasonable assumption here would be the GP questioning the assumed universal truth of:
the same way [ all people ] are disgusted when eating a "powder shake" kind of meal compared to a whole, earthy, flavorful, home-made meal