Actually, the Second Circuit Court determined in 2019 that "Congress specified the fiscal agency relationship for the purpose of putting the (Federal Reserve Banks) under the direction of the Treasury Department in certain limited circumstances"
By claiming that the coin has not been issued yet, then refusing to accept it, the Federal Reserve is also interfering with the issuance of a coin. They are not allowed to do so given that they are an agent of the Treasury Dept.
Janet Yellen has told the WSJ that the Fed wouldn't back the "Mint the Coin" plan because it appears to be a "gimmick". She said that the "Fed is not required to accept it, there's no requirement on the part of the Fed. It's up to them what to do."
Something tells me that Miss Yellen is playing "dumb" on this and doing some political posturing for the Administration.
No one wants to see this go before a Court.