I agree with you about the lack of logic in his argument...and melatonin is a hormone produced by the pineal gland.
He also said 'bisodium carbonate' to refer to 'sodium bicarbonate'...or baking soda...which does not show a lot of sophistication in complicated doping things... like blood transfusions or EPO injections, etc., etc.
Both baking soda and beets are found in many kitchens around the world.
This is another great example of why everyone needs to come up with their own personal scale of measurement...and we will all have different personal opinions which will not all be the same...which is OK.
I personally drink coffee...which has caffeine in it, which has evidence for some performance enhancement..and in my personal opinion...has a lot more published evidence for performance enhancement than for meldonium.
I personally do not consider drinking coffee as doping... and WADA does not consider drinking normal amounts of coffee doping either...while others could argue it is doping since it has been shown to improve performance.
I think either view could be taken as valid.
I also think that do deny a person Thyroid hormone with real hypothyroidism... in real medical need of Thyroid hormone... would be wrong.
....but I think getting a TUE to try to use Thyroid hormone as a PED...without a real medical need... is also wrong.