Not an issue really for liability.
Most of their defense is based on the assumption that you have all the same protections as a network operator. However, as the article points out, this has never been tested in court. So you might be fine, and you might go to jail, we don't know.
And even if you do get network operator status, there are still legal notices and copyright systems you have to comply with.
And thats all just copyright. That article doesn't deal with more serious online crimes.
If the FBI finds someone downloading child porn from your network, you will be arrested. You will have to convince the police that it was someone else. Even if you don't end up with any serious penalties, that's a hell of a lot more hassle than I'm willing to put up with.