Yes, but Satoshi built the protocol before the (0.1) release, before he even released his white paper. The Ripple protocol is not complete and not ready for open source release in this environment - it is in closed beta. Satoshi held his own closed trials before releasing (0.1).
It's certainly likely that he did private trials, probably with some kind of testnet. But not on the public block chain. And certainly not at the scale of Ripple currently with a huge number of users involved.