We're talking about someone who's trying to get more info about the reason why they've been put into jail. Possibly because it would help their case. The agency basically decided on an ultimatum. And no, lawyers won't always do necessary due diligence to make sure their client's case has all documents.
But complete dismissal of leaving them no options aside... if you really think that 70 dollars is a lot of money, just wait until you see the bills towards the tax payer in a FOIA lawsuit for an unnecessary denial.