well it will depend on the size of the town, I'll admit that in my home town of 25k inhabitants it would be hard. but there are a lot of examples of parties getting way out of control because people have been reckless about spreading the word. If the wrong people hear, you're doomed.
Also, what actually happened to him? did more people than he thought show up and start partying in the street? If so, I don't get how that's his fault. It's allowed to throw parties. If I throw a party for 30 of my friends and 500 people show up in the street outside I'd call the ****ing cops and have them remove them, I wouldn't get in troubble aslong as I say I don't want them there and that they are not there for my party.
Hell, I've seen things like this go out of control, not because someone was reckless with spreading the word but because people walked by the house, heard loud music and figured "hey there's a party here!" and then told all their friends. How is that the host's fault?