If proseltyzing were illegal on public property would the ACLU be backing these religious anti-war nuts right to do so at a funeral on public property? Come on, we both know it ain't so. Everyone makes mistakes, no biggie.
The ACLU knows there is absolutely no danger of these whackos converting anyone to their faith and so they'll make a few bucks off Joe taxpayer while giving the appearance they are protecting everyone's freedoms. When there is a real possibility someone might be influenced like the instance I mentioned they fight tooth and nail to shut them up.