The monkey and dog population has needed "fixing" for decades (been coming her since 1993, now living here.). Sadly, government is seemingly impotent and too busy buying toys of war.
Peaceful and smiling Thailand is an illusion. Much like the 36 countries I have lived or visited, violence knows no bounds. I hope the clerk recovers and these thugs receive the wrath of justice, if such a thing exists here. The Red Bull saga is an example.
Gluttony is easily remedied by taking smaller portions, eating it and returning if still hungry. Sadly, the customer(s) in question may not subscribe to that tactic and if a fine is posted concerning waste, then buyer beware.