With the amount of sites that are easily accessed on the dark net though the hidden wiki and other sites. This might of been a honeypot from the start.
On the contrary, why would they announce that they seized the site? To cause more panic, and to exaggerate the actual situation?
In addition, that last point should be considered because even if they used these type of operations, honeypotting would still be considered illegal. So Ultimately what is stopping the supreme power to abuse that power on other people?
This particular platform used tor. It doesn't mean all platforms are using privacy centric anonymous networks. There are incidents with people using kik, Snapchat, Facebook and other clear net services to perform criminal actions such as drugs or cp.