That info is well out of date. The 15 day land border rule was abolished years ago. If you are from one of the visa exempt countries you get 30 days by air or land. There is a limit of two land entries in a calendar year, but not by air.
Googled and attached what came up, as long as the air entry days are correct all good, I reckon that's how he would come from New Zealand where he is now.
That site is run by a law firm and seldom updated. The domain name makes it look like an official government site and confuses lots of people with outdated stuff.
The ask:thailand community, consisting of multiple Q/A groups with over 100,000 members, powers this platform. It is not an official government resource. Our members actively contribute to this resource, and while we strive for accuracy, we cannot guarantee its complete reliability. Assistance to travelers is provided as a community service.