Yeah yeah I know, "God hates fags", "Thank God for dead soldiers", "Thank God for some random natural disaster" and now "Thank God for dead kids". It's insensitive but harmless. The family members of the dead kids aren't going to grief more just because some jerks say mean things, and it's their right to say so.

And that's not my opinion, that's the Supreme Court's:

Speech on a public sidewalk, about a public issue, cannot be liable for a tort of emotional distress, even if the speech is found to be "outrageous."...

http://www.metroweekly.com/poliglot/2011/03/supreme-court-upholds-westboro.html