Such a law should not exist. If a law is so bad that the only way people are willing to tolerate it is with selective enforcement, then it shouldn't be tolerated at all.
Who said the government approval is there to make people tolerate the law? It only applies where foreign head of states are concerned. The government approval was added as is their job to manage international relations - including cases like this.
There is also another general insult law which applies to everyone and where no government approval is needed. This case would run anyway.