That isn't exactly true...if you step in and beat the **** out of the guy....he may press charges against you for doing so. The cops may be all for it, but that doesn't mean they condone it or could let you get away with it. Lamo went out and actively looked for these problems, which if you relate it to the rapist argument this could make him out to be a vigilante....which law enforcement really does not look upon very well.
In the end the yo yo that is the topic of this thread did alot of auditing of computer systems without a written contract or agreement. That is stupid, and could have got him in trouble even if he worked for the companies involved (look at the case with the guy at Intel doing password auditing without permission). Unless you have permission in writing, they can come after you. If you do it without the companies permission and without taking the proper steps for you to be covered legally...they SHOULD come after you. You could very well take out a mission critical system and cost them alot of money.
If you want to be an info sec professional, be a professional. Don't just play one on TV...