So why did you bring it up? The observation doesn't support zoonotic hypothesis at all, although it could support lab leak if we assume GOF was done on a natural or modified virus with a higher IFR rate, such as the ones known to be present in Tongguan where WIV sampled RaTG13.
Similarly -- it isn't clear why you are talking about the cleavage site. You appear to think it argues against some sort of hypothesis. But you haven't stated what you think the most credible lab-leak scenario is and why. It isn't even clear that COV came from RaTG13.