not a crime, of course, but if the bank is actively trying to detect whether customers are really living in the UK then being asked for a verification of adress would not be surprising if your charges come primarily from a country other than the UK.
after creating a Baht account on Wise, when I try to add Baht to the account the menu shown below comes up. One of the options that you need to select is what currency to pay in (to use to fund the account) and THB is not one of the choices. It seems like Wise will only allow you to fund THB account by exchanging from another currency.
maybe that would be a risk if you were carrying a briefcase full of cash when entering the country but there's no risk in a US citizen wiring money into an established account in the US.
by his account of events he tried to explain his lack of an onward ticket by saying that he intended to extend his stay once in-country. In other words he wasn't planning to leave and he had lied about the purpose of his trip being tourism. Sure, a lot of people do that and you never hear of if causing a problem, but it's surprises me that he would given a second chance after admitting that to an immigration officer.
either way he was given every opportunity to fix the problem, even after trying to get away with a fake ticket and explaining that he was planning to work from Thailand as software developer and not to leave after 60 days.