Even more complications for a “why can’t they just…”. It’s almost as if this kind of thing is difficult to do in practice.

> Background agent in the decoy identity that periodically browses the web, retrieves email from a banal account etc.?

No. Think about it for a second: you're a journalist being investigated to find your sources, and your phone says you mainly check sports scores and send innocuous emails to "grandma" in LLM-speak? It's not going to fool someone who's actually thinking.