Originally posted by MF DELPH
That's actually not the case. Thug is generally used for people engaging in criminal or gang related behavior, typically violence or drug traffic. If you are referring to the "distinctions" made when, say, sporting event rioters engage in property damage versus looters from a protest only you might have somewhat of a point, but other people who engage in activities like turf wars, drug dealing, and gang violence do get referred to as thugs even if their ethnicity was not black. For example, Italian members of organized crime or other criminal elements as well as Latino and Asian Gang Members. Hell, Police have been referred to as "Jack Booted Thugs" and "Thugs with Badges". The view that "Thug" is primarily used for Black Activity is a bit of confirmation bias overlooking the other instances where the term is used.
I disagree somewhat. A Latino may be referred to a thug, but for an Italian or an Asian gang member to be referred to as thug by people is much less likely.
You are right that the juxtaposition of police as thugs does exists.
While I agree that there is a usage of thug outside of the racially charged one, to refer to antisocial behaviour generally, it's still extremely linked to black people and much more commonly used in relation to them, not only in the case of riots as you state, but anything related to crime in general.