It doesn't sound to me like their intention is to build community around this code. In fact they explicitly state their intention to merge everything they can back to Apache Thrift, and the fact that they've been tracking upstream closely.

Working exclusively through open source communities like the ASF can slow you down sometimes, so if you need to iterate quickly on something sometimes the upstream review or release process isn't appropriate - even though it might require more work later. They're still open-sourcing their technology, and intend to move it back to the original project. What more can you really ask them to do?