Did anyone here bother to check the bio's of the officials listed on the amicus brief? If so, you'd discover that the many (maybe most, I didn't count) were holdovers from previous administrations. But, conspiracy theories are fun, I guess.

Given the bipartisan history of the lawyers for the Copyright Office and the DOJ, one possibility is that they are basing the amicus on their interpretation of the Copyright Act and related legal precedents. My preference would be that public interface part of API's would be public domain. But that's a preference, not a legal opinion.