First off, the article has a typo. it’s WAT Arun, not WAY Arun. Wat == temple.
As for the gesture Tim makes, it’s a wai, and while it does make sense in this setting, it’s really not typical or expected of foreigners who don’t know its significance and look stupid and awkward doing it 99.9999% of the time.
The degree to which it is executed and when and to whom is a measure of respect and authority, particularly how high the hands are raised and how low the head bowed.