It also proves (1), since it is a response (QRT, rather than a comment) to a tweet describing the trade deficit/exports approach, and starts with "No we literally calculated tariff and non tariff barriers.", and then presents the formula proving (2).
That formula just simplifies to trade_deficit/2*total_imports per country. It doesn't disprove anything it just looks fancier but the two extra terms are constants that simplify to 2. If you do the math it lines up for every country that didn't get the default 10% rate.
