I hate making a scene and challenging people, unfortunately I didn't see any other options at this point. He knew he was wrong, that's why he wouldn't let me speak to a supervisor. If I hadn't had made a point, I wouldn't have been able to get an extension.
While I read the notice and saw that, I don't think that's actually the case. Similar to entering the country, officers have limited discretion and have to follow the policies set forth to them. That's why people are most commonly refused entry for lack of financial proof, not because the IO just doesn't like them.
I believe in practice the actual discretion that's referenced in the orders is to the immigration office so the chief can set particular requirements, not the individual officer.
Everyone hosting a foriegner is required to submit tm30s by law. Most hotels do it everyday without issue. Airbnb is hit or miss, you'd have to ask the host.
Visa on arrival is 15 days, not extendable. Visa exempt entry is 30 days. Your return ticket should match your initial entry validity date to avoid issues, refundable/changable tickets are fine.