Universities (at least in the US) tend to give those out to famous people as favors for lecturing there. (AsAs such, having an "honorary" degree doesn't really mean a whole lot). There wouldn't be much incentive for making up a false story about somebody receiving one.
It appears he did a speaking tour of the US in 1911, and did speak at several universities, so that would be a good place to start looking. I found a dissertation someone did on his speeches from that tour specifically, but it doesn't appear to be available online. My google-fu was only strong enough to ascertain that he did at least talk about California some in the talks.
The only reference I could find to Geneva was that he was there in 1920 when the League of Nations was inaugurated, and became an Undersecretary General for 6 years. It wouldn't be at all surprising if he found some time in the intervening 6 years to speak at the University, nor would it be at all odd for them to give him an honorary degree as part of the deal.