sane atheists are a distinct minority of atheists. Just as the sane are minorities and atheists are minorities and space pirates are.... oh wait... story idea coming.
I get more convinced each day that the only hope to cork these people is to ignore them as you would any child throwing a tantrum. Every time one of these clowns threatens a lawsuit, simply don't respond. If they sue, simply allow for civic "leaders" to continue to ignore them by not wasting money for defense. Then if some mindless twit of a judge decides to "hear" the complaint, these same civic leaders should ignore any ruling regardless of how it goes. Just don't read it.
As long as otherwise functioning adults continue to pay attention to these children, they will continue to push the envelope as any child will do.