@Bob *********
did he already go and make his appointment to apply for the 90 day Non-O? You can't just walk in and do it, you make an appointment and they give you a hand out that lists the documentation required.
The US consulate can't do anything about it, AND the thai immigration office can ask that a person using an affidavit of income from a consulate show their bank statements to back up the amount put on the letter is real.