A huge amount of OEMs in Android does this as well or release late. Let's not jump the gun on a company doing amazing things and give them some time to do it.
I think it's unlikely that they intend to release the source as they talk about "Partnering for free!" for "licensing", so clearly want to retain some pretty tight rains on the code. "Profit sharing" is a term they throw around a bit too.
It's based on open source Android (incl GNU GPL parts) and yet doesn't publish the code. They shrug off such questions in their official forum.