Is it ethical wrong in this case, to wish those persons to get beaten up one day, by one of the people where they fueled their hate (who do take it out on other people for real)? So they reap what they sow?
If you're in a position where you're actually making the decision between letting these harmful practices continue, or putting a stop to them, that's different. But in this society, such people are more likely to be journalists and justices than vigilantes, so violence is still inappropriate. I think the scenario you described, of those incited to violence turning on the inciters with violence, is rather unlikely in reality, and it wouldn't necessarily be a good thing.