also, if he can’t get the paperwork, can’t he just go into immigration one day after his extension expires, pay the 500 baht fine for overstay, the 500 baht fine for not canceling his extension (1 day) and then leave the country?
When you check in wherever you will be staying when you do your extension, ask them for a print out of your TM30. They will either helpfully print it out and hand you a copy or insist that such a thing doesn’t exist.
If you have one, bring it to immigration with you when you do your extension. They may or may not ask you for it.
Other than that you need never concern yourself with TM30s as a tourist.