ASCAP is as evil as the RIAA.
Hardly. ASCAP serves a very, very useful purpose. They protect the small guy from having their songs ripped off, mostly by the RIAA. If you put together a track of two trash cans banging together to a beat and get it registered with ASCAP, and ASCAP finds out that someone (be it bar owner, RIAA or any other band) is using that track in live performances, they will battle for you to get your licensing fees.
ASCAP is usually just the messenger. They don't normally go around trying to find songs being performed that are not in the public domain, they are usually tipped off about it by someone claiming they are owed licensing fees.
In this particular case, I wouldn't be surprised if the RIAA were involved as the person "tipping them off".