Mob action is not only justifiable but some times nessecary when attempting to inact a change. Resonably a riot is not always nessecary and should be avoided if at all possible but taking mob action against someting is often the only way anying is ever changed. This is esspecially true in countries were the goverment is infact not a democracy, since in these countries mob action is one of the only ways to get the goverment to change something. Yet America which is considered a democracy resorting to mob action is often the way change comes about. Based on the principle that life liberty and the pursuit of happiness are unaliabel rights any time those rights are justified people have the right to resort to mob action. Many movments throughout history have only become realities through mob action such as civil rights movement and countless other revolutions through out history.
As for the statment "rebbelion is a crime unless it is sucsessfull" nothing could be more true. Through out history as groups of people rise up either there rebelion is crushed making them simply a minor glitch in histroy or the rebellion is sucsessfull and thus they are glorified as the founders of a new idea. This is supported by events in history such as the civil war, the confederate states were treated like criminals because they lost yet if they had won then it is very likely that they would now be there own country.