I didn't read all of your post, the first paragraph shows your lag of thinking, I could say "he could have been using drugs, he could have had a medical episode, he could have been physically frown over, etc.. so again, enough of the guessing. If you've been in Thailand, for some time, you will know that Thai rail height standards, do not exist, and are, in most cases, too low, making it easy for people to go over.