You can say "cash is trash" and "Bitcoin is the king" 100 times, but when you go for shopping, you have to pay with fiat, you get salaries in bucks. So maybe cash is trash, but it's irreplaceable "trash" now.
Yep, cash is not trash because we still use cash to buy anything we want. No matter if we use credit/debit cards, as long as that is mean about fiat, that still cash. Many countries still use cash too, and many of them do not use bitcoin as the payment method. Maybe until bitcoin can be used as the payment method, and cash is replaced by bitcoin, then he can say that cash is trash because cash will not be used as a payment system.