It's not new news. It's just a new development in that news. Spying was already a topic with Luigi and Robin, but Charlie Kirk's assassination was an enormous deal apparently, with world leaders the world over paying respects. That kicked off a whole search engine based registry, which MSNBC reported on. Some of this involves a doxxing process, and even if this wasn't already made clear, you could put two and two together and get an idea that Lemmy would play a huge part in this and would be the thing all the paper trails lead to.

As for knowing exactly who is working with the NSA, people working for the agency would follow the same tactics. They entice a reaction, fake-debate with people, mine people for knowledge while knowing who probably is and isn't sympathetic to extremists (even though they would play it safe and treat everyone the same). They're not afraid to outright sit down with trustees though (recall the story of Orwell ratting out his comrades), and the crew behind the search engine registry isn't classified. Some people will brag and say they're working with the government as a flex, and occasionally it will be consistent with events surrounding suspects.