Because you never know what trivial bit of information may ultimately prove to be vitally important.
Didn't SAWS check some pipes for leaks not too long ago where they pumped smoke up from the sewer system? Perhaps this guy was one of the ones who had smoke coming out of his pipes.If so, then it's way past time for the dude to take his sign down.
I guess it could have been about that. By the way, contractors did the actual testing. I saw them a couple of times. In one neighborhood where I was working, some guy called the fire department. Apparently the smoke was coming from somewhere it shouldn't have, on his property, and he thought it was a fire.