IMO
Here in Seattle, we have laws against moving signs. The only exceptions to this law are barber shop poles, which were “grandfathered” in. It’s not about the particular message, or free speech, or anything else. It’s about the fact that moving signs are too distracting to drivers. It’s a traffic safety issue, pure and simple. I don’t care if they want to put up signs of aborted fetuses or dead soldiers, as long as they don’t do it on the freeway. This particular sign has already caused two accidents, how long until somebody kills somebody else because they were intentionally distracted by somebody with a “cause”?