This is a good use case for a blockchain. AI companies can run their own nodes so they're not bashing infra that they don't pay for. Concerned citizens can run their own nodes so they know that the government isn't involved in any 1984-type shenanigans. In the sealed-for-X-years case, the government can publish a hash of the blocks that they intend to publish in X years so that when the time comes, people can prove that nobody tampered with the data in the interim.

The government can decide to stop paying for the infra, but the only way to delete something that was once public record should be for all interested parties to also stop their nodes.