“there are exceptions, such as during WW II, when Rabbanim did march to Washington.”
That didn’t really work out, did it. But R’Aharon Kotler, R’Kalmanovitz and Irving Bunim had some success going behind the scenes. However, I agree, that in such a grave situation where so many Jewish lives are on the line and you are not criticizing the government but begging the government, a public outcry might be in order.
Mishkav Zachor isn’t such a situation. And we should not “express” our disagreement. We should keep our mouths shut.