I said suspicion, not evidence. The suspicion arises when you try to answer the following 2 basic questions:
Who wants to deanonymize TOR users the most?
Who has the resources to run TOR servers and provide the service for free and why?
Or put another way, apart from a few idealists like the Calyx Institute, nobody in their right mind would foot the bill to run servers mostly used by hackers and pedos. Therefore, the most likely operators are law enforcement and nefarious barely-constitutional three-letter agencies.