Why do you think that? Insulting the king's dog is just a "dogwhistle" for insulting the king. By insulting the king, you break the social cohesion of a country. The respect for the king is one of the major things that has held Thailand together, and kept Thailand as one of the few Asian countries that was able to avoid European colonization. Breaking this social cohesion makes civil war and the breakup of the country more likely, which is a bad thing.
Here are some other harmful things.
Arguing for anything that raises taxes is arguing that people's money be taken from them by force of law - clearly harmful.
Arguing for reducing taxes is arguing that the government have less resources that can be used to fund social programs - which can hurt people who depend on it - so clearly harmful.
Arguing for tougher prison sentences is clearly harmful to those people convicted of a crime.
Arguing for lighter prison sentences is harmful to the victims of crimes.
Arguing to curtail free speech on the Internet is clearly harmful as can suppress valid criticism of the government.
In addition, the wonderful stuff about this supression of arguments for things you harmful, is that you can also suppress the arguments for why you should be allowed to argue for them.
Arguing for genocide, or deportations, or coercive "cures" for gayness or etc etc is clearly harmful.
There is no reason to make space for haters. Kick them off the internet.