I'm not disputing the legal tender status of nickel dollars.
My argument is that legal tender status concerns only the validity of a piece of currency towards payment of a debt, and that as such, there is no obligation for a bank, or anyone else, to exchange one type of legal tender for another, in other words, banks are not obligated to accept nickel dollars in exchange for other coins, banknotes, or as a deposit. The only time the legal tender argument comes into play for a bank is if you were to use them towards payment of a debt (e.g. credit card bill).