Thailand can do whatever it wants today regardless of a U.N. treaty. Extradition deals can be made between countries. Additionally, Thailand can issue arrest warrants for whatever it finds on your social media accounts, whether those are enforceable or not is another question. The article doesn't mention anything about making international enforcement mechanisms easier.
My point is: The majority of our data is being tapped by government entities and can be used against you already. This treaty is just saying the quiet part out loud once again. No one seems to care or else we wouldn't have a massive intelligence apparatus controlling parts of our society.