It allows to divert a discussion, for example if a Russian politician/minister is confronted with the topic of the Ukraine in a press conference or an interview

It allows to divert a discussion, for example if a Russian politician/minister is confronted with the topic of the Ukraine in a press conference or an interviewer, then it would be easy to stop that discussion by responding with these arrests. The comparison to the NSA isn't that valid, since it is well known that the NSA does this, but I don't think that there would be many persons who would know a single thing the FSB has done in Cyberspace, unlike them being famous for poisoning and throwing people out of windows.