I've come across this paper about "De-anonymizing Social Networks". The goal is to use Flickr network to de-anonymise Twitter's anonymous network, but the experiment section doesn't seem to be right.
At section 6 Experiment, the author crawled the API of Twitter and Flickr that exposes the mandatory username and optional names and location. He then goes onto explaining how to deanonymise.
My concern is, surely those graph he used in his experiment are not anonymous, they clearly have a mandatory username and (sometimes) names to go with it. Wouldn't it be wise to anonymise the identifiers or maybe my definition of anonymous social network is skewed. It seems to me, that he used a public graph (Flickr) to identify users on another public graph (Twitter), which seems wrong. Can someone offer me any insight to this?