All of the flashing logic is client-side. As a bonus they could archive the whole site. But even if just the firmware blobs were available it would be a huge win as developing another flasher is probably pretty easy with the provided documentation. I suspect that it wouldn't be hard to identify and download most of the firmware that could be used (I don't think there are many controller revisions) but distributing those will be a legal grey area without a proper license from Google which presumably owns the copyright.