This is not to mention that even if it were open source, it is not likely that the tool chain used to create it is even available, let alone open source. Firmware blobs are just a fact of life, for now at least.
Intel has licensed GPU designs from third-parties before, but typically only for their low-power (Atom) chips where they just didn't have the technology in-house.
Here, we're talking about a new micro-architecture for Intel's premium product line; I would be very surprised to hear Intel licensed anything in the design from third-parties. If Intel wanted their tool-chain to be available, they could make it so.