But truth be told it's probably just an Internet tantrum where he's lying instead of actually having massive brain damage. But can't rule it out tho

What I think Tja means is that, because you can get the deposit refunded later, you should effectively deduct it from the retail price when talking about the overall cost of the product. But that position assumes everyone actually goes to a bottle deposit to collect the refund, which in reality barely anyone does. So it's still a specious point to be arguing about.