Not sure if this will apply, but could they not plead the fifth amendment on this warrant.
That isn't the protection of the 5th. The relevant parts of the 5th are protections against self incrimination and due process requirements.
Warrants usually don't (but very rarely do) have something to do with self-incrimination. They are a demand to seize an item for evidence purposes. Even so, US courts have treated this type of data as business records which can be obtained through several methods. They aren't trying to incriminate Google, they are trying to incriminate someone who uses Google. The due process issue doesn't apply because they DID follow due process. They got testimony of the probable location and contents of the data, they signed a statement of probable cause, they got a warrant specifying the exact items to be seized and searched, that's due process.
The fundamental problem is one of jurisdiction on the Internet. It is an open problem.
On the one side, companies should not be able to move data to another country in order to avoid law enforcement actions. If that were allowed, every major company on the globe would open a data center in that location and preserve all copies of documents in that haven. There (arguably) needs to be some reasonable way for law enforcement to access data stored remotely so criminals cannot merely hide their crimes by storing documents in a server located abroad. Governments must be able to enforce their own laws, which means some access to information.
On the other side, governments should not be able to violate rights of other nations with impunity, including digital privacy rights. If that were allowed, companies could leverage the most oppressive nations and the most aggressive nations to compel discovery of their most secret documents. There needs to be ways for people to legally ensure their privacy and protections granted by their own governments, and individuals have rights to be secure from interference.
Like most things in law, it is a tricky balance of between rights, benefits, and interests. In criminal cases society has a security interest in getting the criminal caught, but that interest competes with the interest of security for individuals to be safe from intrusion. There is also the balance of one nation's sovereignty and another nation's sovereignty, the one wanting access and the other wanting protections. There is also the issue of an individual's rights to secure their property how and where they please, versus storing their property in a way that violate's society's rights to security by identifying criminals. None have an easy answer.