Well, everyone has a right to express their opinion. And people are used to a certain set of opinions being expressed in “large” ways. Expressing the opinion is not illegal. Nor should it be. So most people would not take action as it is legally protected. A commenter in another thread said it was taken down for violating zoning rules and such. And that is reasonable. Expressing your opinion is fine, but forcing others to see your expression should have some limits. Just like ads should as well.