You can replicate within groups of datacenters which fall under the same privacy rules. Thats more than enough to run a centralized global social network, even though I'd love it for making it impossible.
I'm not talking about replication for disaster recovery, but replication to avoid intercontinental round trips.
If my actual name is stored in Europe, my US friend must request the data from the USA just to show his friends list on an HTLM page... (is that a transfer too? is it forbidden too?)
Without replication between locations, you're stuck: replication IS data transfer.
With such a ruling, you can't implement an intercontinental social network anymore.