I would contact the airline first. Ask them what documents they accept for him to travel. Get him to take the reply email to the check-in desk. Next go to Thai immigration and ask them what is required. If you go by all replies on here you may get it wrong. Good luck 🙏
I don’t think ‘you’ need to worry about this. Only proof of where you are staying. Copied this …. You do not need to submit a TM30 for yourself. Instead, this must be completed within 24 hours of your arrival by the owners of the lodging where you are staying. A fine of 800THB, increasing to 1600THB/person for the property owner, can be imposed for failure to accomplish this.