It is a distinction that is relative to circumstances, yes, but circumstances are what the distinction refers to. It is about power and who has it. The hypothetical you pose is an example of power and its use. The corporations have the power in that hypothetical situation and are using power to abuse workers who lack power both before and after consideration of diversity policy, however it is present. Without more specifics I can't tell if this is a situation of retiificatory justice or just an excuse by the corporation to defend unjust actions.

I can't see a justification for violence in protests. The reality is that protests there are people who come to speak for justice and there are those who come to commit violence. "Everything's fine until the anarchists show up," is a common saying. Of course, we should equally condemn law enforcement when they resort to unnecessary violence.

I don't have a binary view of protest except in that, yes, one is either targeting those who are the legitimate focus of the protest (actually the ones committing the injustices being protested) or targeting ancillary people trying to get them to be angry at the ones committing the injustices. It's a difference in strategy, the latter being justified at "raising awareness." My argument in this article is that the latter is an ineffective and unethical strategy.