Isn't there a degree of "apathy" vs. "honesty" here? A person could be fully honest, but just not care enough to take the time to contact the owner of the wallet. It doesn't seem they considered that in the study design?
I don't want to say that the study was a failure, because I don't know what the standard for a successful study is, but it reads like they are trying to gloss over the fact that they did not actually end up measuring honesty.