The point is, assuming that gain-of-function would have a viable path at turning a bloodborne pathogen into an airborne pathogen, rather than simply making an airborne pathogen more transmissible, is disappointing in its complete misunderstanding of virology. It de-legitimizes the point they're trying to make.

Lab leak theory is more than a big "what if", it has merit to it. To try to make an analogous argument toward how ebola might become more transmissible in a similar manner ruins their credibility.