The radical atheists have an agenda of attempting to thwart any and all religious activities of others. They realize they don't have any legal ground on which to do this in most circumstances, but if they can find even the smallest of potential legal footholds somewhere, they're going to climb on and keep going until someone stops them.
What they really should do is mind their own business and leave other people alone. Instead they have to seek out these circumstances where they can challenge the beliefs of others, because they apparently have nothing better to do than to cause problems.
Funny, many world religions spend a lot of time helping people, yet it's difficult to find atheist organizations doing anything but causing problems.