Extremists always exist, and will jump onto any legitimate political group that is nearest to what they want. One ought not tar all, or ever hint at doing so, simply because of the infiltration of the few.
Rioting seems to produce results in France. Sad really as the example encourages others to try the same. We need authorities that listen to the will of the people, not manage/use/herd them. If this occurs then there is little worth protesting about.
Meanwhile it's a massive loss for a legitimate political party/pressure group to associate with well known folk who have loads of detrimental baggage from past activity. One can only hope that UKIP are not beyond restoration back to when they had just the legitimate political agenda. But if moderate UKIPpers get disgusted and leave, that becomes less likely. And that plays into the hands of the established main parties, who no longer have to take account of the independent voice of conscience.