Idk about entering on an expired passport, but IF he can get his ID card then he can just overstay on his foreign passport and they will waive the fine.
I'll let others speak as to the non o and documentation requirements, though possibly the 60 day family extension may be available. Though it might require Thai ID, I'm not sure.
You should join Thai Citizenship Group, if you're after info on him obtaining his first Thai ID card.
there's a paper form you fill out at immigration, you need a passport photo and photocopies of passport ID page and visa exempt stamp page. Also possibly a copy of TM30 report (done by hotel you're staying at, ask them for a copy). Normally there's a photocopy shop and photo place near immigration.
From memory I believe Kasikorn wanted my rental contract & a utility bill in my name with my address on it. + the document from your school and passport I think should be enough.
I opened mine at the Sukhumvit 33 branch (opposite Emsphere), it's reportedly reasonable foreigner friendly.
only 12k aud & 2yrs wait for that Australian (spouse) visa, plus up to 100 documents proving you're in a legitimate relationship . Marry a Thai and you can get Thai citizenship in a few years as well, if you meet the requirements.
not every instance there's way too much variability, but he does say it very often, as do others. Yet I don't see people say they aren't a requirement. Maybe x border don't normally ask, or a less nuanced response, but no one says that it's not a requirement that can't be asked for
Brandon replies to almost every post of someone with questionable history to have the 3 proofs, I and others have many times too. Not once has someone said it's not a requirement. You'd think they'd be replying here