The short answer is, that is correct. I could not find the driver/feature/firmware packs that Microsoft is releasing for the Surface Pro 3 in my clients Windows Server Update Services WSUS, so I googled it for a while then gave up and asked Microsoft Partner Support and this is what they said:
From your description, I understand that you want to know whether Surface Pro 3 firmware/driver packs can be deployed via WSUS. If I have misunderstood anything, please feel free to let me know.
Based on my research, I am sorry that WSUS does not suppport updating Firmware/Driver packs for Surface Pro 3. You can refer to this blog:
“Note – They cannot be installed via Windows Software Update Service (WSUS).”