He was an NSA analyst that told us about things like 5 Eyes. He commited treason by revealing classified information because he took a stance against what he concluded was overreach and problematic behavior and decided to become a whistleblower about it

He did this knowing the punishment was death, so he found refuge which unfortunately is russia.

At this point its not hard to imagine Putin would want to convert snowden but no one who is claiming Snowden is a shill/russian asset is doing so based on any evidence, its all anecdotal and opinion because Putin would absolutely use him if he could convince him