Content already released, yes. The post says nothing about being able to make new things under 1.0a, which is where a lot of the nervousness comes in for people.
FWIW, I don't even believe they ever wanted to try to claw back e.g. the 3.5 SRD, so I'm not as concerned as other folk here. (But it's also clear that if they have no such intent, they'd need to make it legally binding for folk to trust them.)