As was noted, the postcard said the Watchtower Society received no money from the Knocking project. Still, all the early hype for Knocking being "fair" and "objective" is contradicted, I think, by this postcard. Knocking does mention both sides, but it's slant is clearly sympathetic to the JWs which is why they can market it like this to JWs.
Perhaps someday someone will do a documentary on JWs like the recent PBS one on Miormons.