I remember, going back a few years, how สวัสดี would be transcribed as swasdee, as that's how it's spelt, but not how it's pronounced. But that's the beauty of the Thai language, and part of the fun of learning to read it. His name is, I guess, from Sanskrit/Pali, like most Thai names. And before people start on about crazy Thai this and crazy Thai that, consider, just for starters, Messrs Cholmondeley, Wemyss and Beauchamp!