I'm totally with Thai Airways on this topic. It's got nothing to do with what a lot mention here "Thai Ego". It can be related to Ego only if the passenger would comment for example on dirty toilets on the aircraft. In that case having dirty toilets and suing the passenger would be an absolutely wrong thing to do. This is just an example and i'm NOT saying that there are dirty toilets anywhere.
It have been studied and proven (just search on the web) that our brain remembers negative responses much better then positive... If Thai Airways would go into explaining why they diverted the flight, this would never make it to the headlines and the person responsible for the original post would not probably even read the reply and people who did see that post would only remember negative connotation in which Thai Airways was mentioned. Now that person got slapped back with a lawsuit. This news made it to the headlines and people who saw this (of course not all but at least some people ) including the original poster will actually THINK AND CHECK before letting their rage out into the www.
I wish I could behave the same way Thai did sometimes as it would seriously reduce the amount of idiots in my proximity. The problem is that it costs money and I don't consider cases happening in my life worthy of spending 25k (this is what my lawyer said he would charge me) just to file a defamation lawsuit.