I point this out because of this stories like this one hyping the canceled Tor talk at BlackHat. It's titled says the talk was "Suddenly Canceled". The adverb "suddenly" is clearly an attempt to hype the story, since there is no way to slowly cancel a talk.
The researchers are academics at Carnegie-Mellon University (CMU). There are good reasons why CMU might have to cancel the talk. The leading theory is that it might violate prohibitions against experiments on unwilling human subjects. There also may be violations of wiretap laws. In other words, the most plausible reasons why CMU might cancel the talk have nothing to do with trying to suppress research.
Suppressing research, because somebody powerful doesn't want it to be published, is the only reason cancelations are important. It's why the Boston MTA talk was canceled, because they didn't want it revealed how to hack transit cards. It's why the Michael Lynn talk was (almost) canceled, because Cisco didn't want things revealed. It's why I (almost) had a talk canceled, because TippingPoint convinced the FBI to come by my offices to threaten me (I gave the talk because I don't take threats well). These are all newsworthy things.
The reporting on the Tor cancelation talk, however, is just hype, trying to imply something nefarious when there is no evidence.