My family have stopped going together to the cinema for a while now, ever since my son started gaining his own opinions on a subject. Last movie we saw as a family was “Creed 2” I think. During the “anthem” my son, along with about 80% of the cinema didn’t stand but my wife, a staunch royalist, did. It wasn’t pretty. All through the movie my wife snapped at our son who, unwisely, argued back to his Mum. We had to leave in the end.
Now, I watch a movie with my son, we both don’t stand. I go with my wife, we watched “Oppenhiemer” recently, I stand with her. Just to keep her company ????.
Its not illegal. Some time ago, Prayut advised young Thais to be brave against their peers and stand in support of the institution, even if they are bullied for it.