I am an economist, and I have no idea what that means. Sounds to me like confusion over two things: (i) the difference between "supply and demand" and the "quantity supplied" or "quantity demanded" and (ii) equilibrium. The circular logic is a tell tale sign. Price goes up, so people demand less, so price goes down, so people demand more... That's the whole point of equilibrium. Where does all of that net out.

I think they are trying to say that demand forces supply.

Exactly, that's a huge mistake. Shifts in demand cause shifts in supply? That's not obvious at all. The whole point is that supply and demand have different determinants, but they mutually determine quantities and prices.