Let me start by saying that the actions of the members of the Westboro Baptist Church are reprehensible and disgusting. People whose loved ones die, no matter the cause or manner, should be permitted to grieve without disruption by zealots who care nothing for others and only for their cause. But it seems the lawsuit seeks a restriction of protected speech. So, while it attacks the outlandish behavior of the Westboro protesters, it also, if successful, could have a chilling effect on others exercising their First Amendment rights in other situations.
It seems to me the more prudent approach to this problem would be for the authorities to create an area for the protesters - close enough to be associated with the funerals - but far enough that they don't disrupt the services.
This is done in New York City all the time. Protesters at the United Nations are given opportunity to gather across the street in a plaza. Where they can be seen and heard without disrupting the travel of those entering or leaving the UN.
The Westboro goons have rights. But so do those burying their loved ones killed in the line of duty. There's no reason both sides can't be accommodated without setting new rules that could erode the First Amendment.