When you are exposed to information that it would be improper to act on, you generally have to demonstrate affirmatively that your decisions aren't based on it

When you are exposed to information that it would be improper to act on, you generally have to demonstrate affirmatively that your decisions aren't based on it to stay out of hot water. It's the same deal as clean-room reverse engineering, where you need separate teams with a lawyer as a firewall to prove you're only replicating certain aspects of the source. It's not that presumption of innocence isn't applicable; it's just, when your defense is that you tracked provenance in your head and were careful to ignore the tainted information when thinking about certain things, it probably won't be hard to prove you guilty.