They definitely should have shown an example, or referenced something else that backs up their claim. I think it was you who made the good point that, when it comes to data usage, the mean may well give you more meaningful information because of the outliers!
I can see the median being useful for answering what the cost of one more server/agent/whatever would be, but that’s not what this paper is asking.
Now, I do agree it would have been nice to demonstrate this, however it could be genuine.