Sure it’s legal tender but it’s still stupid. So he’s unhappy paying the bill. Why does he put it on the employees? He’s an ass.
I bet he didn’t go around trying to stuff dollars bills into coin slots (when such things existed) and then complain that the machine wouldn’t take his legal tender.
He would not be happy if he bought something at a store and they gave him his $19.37 in legal tender pennies. He’d probably run to the media and complain.
And he’d love it if he had gotten a tax refund from the feds in pennies.
He could have used the time be wasted pulling this childish prank to do something useful.