This bothered me a lot too. If he can tell the difference between 'tap v bottled' but not 'tap vs soma'... then 'soma vs bottled' would intuitively have a diff

This bothered me a lot too. If he can tell the difference between 'tap v bottled' but not 'tap vs soma'... then 'soma vs bottled' would intuitively have a different result if his conclusion is 100% correct. I suspect there's more to it, but the author was focusing on winning an argument so... I guess that killed the curiosity required to dig further for a more thorough conclusion.