Anonymizing photos of the violent ones is therefore likely to support their actions by making accountability less likely. To scrub ethically, limit it to the non-violent protestors. To support non-violence, better to help identify the violent people -- police or civilian -- the opposite of anonymizing them.
I should add: In all of the streams and pictures I've seen, all (most?) the looters or violent people were wearing masks, ensuring their anonymity. If anybody's being protected by measures like this, it's your average peaceful protestor.