Why would you participate in a protest that if the ppl knew you were jewish it would turned against you?
You can't really be on the same page then, could you?
You can show subtly that you, a Jew, cares about racism, but if you flaunt your Jewishness, there may be some (only some) who may use the chaos to take out their anger on you.
Not saying it's probable. I just mentioned it as a cautionary measure.