Things are kind of bureaucratic like that here too, but it's okay to volunteer while on work visa, but a big no-no to work on a volunteer visa. Well, the last few years have nearly crushed international NGOs in Cambodia, and now the longest visa a volunteer can get is 3 months, so basically you have to commit to a multi-day trip to Phnom Penh 4 times a year, very inconvenient and discouraging.

I agree, our man in Krabi is a legend, and it's obvious he loves his work.