This may sound stringent but people have gotten into trouble for more trivial activities such as karaoke.
I hope you've cleared this with immigration or everybody attending could face deportation.
I hope you've cleared this with immigration or everybody attending could face paying a bribe.
Although they primarly bust foreigners that work and do business with Thai people, aka take their jobs away.
99% nothing will happen and you have a good time but pray not to be the 1%.
More importantly though, they are responsible for their attendees and should consult lawyers or immigration as to whether it is legal or not.
Having consulted immigration previously myself I firmly believe what they plan to do is illegal.