OK, maybe the dev is just new to this, seems like they thought since there was nothing built into their Desura or GG interface to add the Steam keys themselves, then it couldn't be done. Hopefully once they talk to GG and Desura, delivering Steam keys will be back on the table:
We're not withholding keys for any reason, we're just not sure how to distribute batches of Steam keys to customers on Desura or GamersGate. If there is a way, then there's nothing in the back-ends of either service that allow it, so it must be something that Desura or GG handle directly.
Let me check with them and see how it works. We'll update the policy accordingly.