I have a very hard time imagining American(/Italian/British/...) cops arresting on the spot a couple of Brazilian police officers handing them over a drunk disruptive American(/Italian/British/...) passenger whom they restrained after being asked to by the plane's crew...
They would if that passenger filed a complaint of assault, which is what happened here. Whether that complaint could be substantiated by further investigation is a different matter, and the FAMs could have called all the witnesses they wanted to back up their statements. That's a bit more difficult now that they have fled the country without waiting for due process.
FIGJAM_SEA, I'm not sure what your problem is with Brazil, but it's not "my" country. I live and work here for a US company, much as I've done around the world for more than 35 years, so I have seen my share of crap countries. Brazil isn't the best or worst place I've lived, but neither is the USA. Each to their own.
TTFN