YouTube response and litigation?
OK, I'm sure there are ASR members who are lawyers here, but if I were to take a guess, you would need to hire an expert to prove why Amir's testing methods, which follows industry standards of CEA 2034, are "botched" and explain why industry standards are "botched" and you would have to prove intent of libel. You likely would have to provide your own measurements from an laboratory that is certified under perhaps ISO or other standards and if that's if the laboratory is willing to entertain the idea of measuring your speakers using non industry standards and able to justify why. That's a tall order to achieve Mr. Alexander.
Or I suspect you may plan to bring forth a suit with the intent to intimidate or to cause legal cost burden.