If you signal a thing that you don't believe, as is assumed that GS was doing in the hypothetical you are responding to, then you have behaved deceptively. You

If you signal a thing that you don't believe, as is assumed that GS was doing in the hypothetical you are responding to, then you have behaved deceptively. You are free to argue that GS does believe that Tesla is overvalued, but it is not relevant to an argument which explicitly assumes the opposite.