How likely is it that a man just shrugs his shoulders and says: "Ok, she ran away with someone else"? I also doubt that he worked at a Thai university "for 20 years", he might have done that briefly (common retirement age here was 60 until recently).
Anyway, the main disappointment seems to be the lack of engagement of her family to push the search from the beginning. This would not be atypical for Thais, in my mind it is some sort of autism. If I'd disappear, my family would most probably stir up a lot of trouble. Thus this may be another example of how low some Thai think of the individual human life.