Haha, I'm not really concerned about the consequences. Just trying to understand the law. Continuing to break the law because there's a low chance of being caught still makes you a criminal.
Anyway, when someone uploads some illegal data to the Steem blockchain, every single witness' hard drive holds this data. Not just witnesses, any one that wants to run a Steem node. That's the problem, and how it differs to your analogies.
Is it possible to encrypt as it passes through your systems? That would probably make all the difference (I'm illiterate so that might be a stupid question)
Doesn't matter if it's encrypted or not, it's still illegal.