Agree, he fulfilled all requirements for visa exemption. That’s Qatar’s responsibility and right to check and do their decision. Qatar can’t act as an “immigration” into Thailand, but what’s more important here is if this will show if there’s some kind of communication between the immigration at the destination and the airlines during check in.
We all know this, but this is the case and what happened. The airline it self doesn’t have the authority to deny people hence to immigration, unless the immigration put an alert in someways in the system for this person. We know he was controlled and questioned at the airport when he left as he did several entires on exemption.
Typical Thailand, but your social security number should be the same. Maybe the solution would be to get a new passport also in your married name, or open a new bank account in Thailand in a new bank with your passport and transfer the funds.
As you’re American your embassy doesn’t offer to give you an affidavit letter to confirm your income, so it’s no way around funds in your bank.