Access to the data as currently provided on the site is free and will continue to be free. If the site becomes too expensive to maintain the data will be given to someone who can continue to provide it for free.
Automated Genealogy does provide for-fee search services which do utilize the census data. The revenue from these services pays a fraction of the costs of hosting the site. Since the data is provided for free on the site people will only pay for the automated searches if they think the search process itself is worth the cost so it is the search process not the data that is being charged for.
The model for the transcription project relies on everyone deriving a benefit. Everyone benefits from free access to the index and that is what motivates volunteers to provide free labour. Automated Genealogy benefits from publicity and good will, and by having more data to perform automated searches on. It will never be in our best interest to try to revoke access as that would make us a pariah in the genealogical community. We think the 1901 census index project is an exciting illustration of how internet technology can allow people to cooperate and collaborate on a scale that just wasn't possible in the past.