If the host canceled, Airbnb refund process starts automatically. Of course it takes a few days for the guest to actually receive the refund, nothing related to Airbnb or the host, it depends on the guest's bank policies to make the refund available.
I believe Rodney believes that it is Airbnb's fault that he was "left homeless and at risk wandering the streets of Rio"and should be compensated (extra $$$/refund for his hotel) for that. I think that is what he means by "reimburse my experience".
Sorry, if that is the thought, I totally disagree.Cancellations may happen for various reasons (even extenuating circunstances) and guests should always have a back up plan.
As for the host, many things could have happened..and even if it was not an honest mistake, the host has always the right to cancel the reservation,a nd he will pay the price for this. He offered to accomodate the guest , with his presence. The guest complained to airbnb, host canceled. You get your money back, fair enough. Rodney, you had a choice. Didn't have to be left homeless or have paid $400 for a hotel, could have only spent some time sharing the space with a Rio native, get some tips and clues about the city.