Technically that right only exists if his checking account is also at Chase.
Otherwise, they’d need to file a judgement against him, which won’t happen until he’s around 90 days late most likely.
I assume he has his DDA with Chase.
But even if he does not, I would not be too surprised if his Chase Mastercard contract also allows for offsetting from an outside bank.
He should have taken the advice of the CSR to do that telephone transferr. He made a mistake in going delinquent. He made a mistake in refusing to pay over the phone.