Setting aside the political hay that the RNC would make about it, is there any reason why RNC would have standing to object if Google explicitly refused to deliver RNC email? The contract, if any, is between Google and the mailbox owners. Google is not a utility -- they don't have to work with all comers.
Edit: a much more amusing outcome would be if Google delivered the emails, but first re-wrote the WinRed links to point instead to ActBlue...