Will someone steal my grand piano?

Highly unlikely. Grand pianos weigh thousands of pounds and do not fit through doors.

That's just unacceptable. Regardless of whether this ever happened to EJ or not.

I'm all about startups having a sense of humor and personality. I think that their mistake is not following their answer up with something like this:

"But seriously, you rent at your own risk. Make sure to lockup or move all valuables to a friends place. If there are any problems, contact us 24 hours a day at XXX-XXX-XXXX"

I agree with you, its perfectly OK to set a tone and personality for the site – but that information to me is critically important to users of Airbnb and why to this day I haven't used Airbnb. It never seemed clear what would happen in this event and now we know. You are on the hook.

FYI In her blog post, EJ points out that Airbnb also lacks a 24 hour customer support phone number.

I think certain parts of FAQs can breathe a bit more and inject humor. Others can't. Payments, renter sec., etc are sacred ground. Funny is a disarming quality; you want these sections to reiterate strength, confidence and professionalism.

Agreed, but having a sense of humor is fine until it becomes reality.

...and rather than update the answer to reflect the traffic they'll be receiving to that question, they just removed it.

I guess they're still in hope-this-goes-away mode.