Currently $redact is more like ... um.... $remove. When conditions are true, it strips all the content away; there's not even a trace that it existed, which is slightly different than redact.

A very useful variation of this would implement the following actions to replace info instead of stripping it away:
$$VALUE: A specific value
$$LOREM: Give a certain keyword arg (SSN, phone, address, email), produce a random but construct-appropriate value). VERY important for testing where the value has to bubble up to the business logic in a form that doesn't blow up the business logic.
$$RANDOM: A totally random value appropriate for the type
$$HASH: A salted hash representation of the content, guaranteed to produce the same digest for the same field value. This is very important for consumers who need to test with "concealed" data but in pulling it into their code logic, need to keep the proper distribution of values. The salt is scoped to the collection. As long as at least ONE record is in the collection, the salt lives for that collection.