I get your point, though risk is subjective. The level of the risk is only as large as the people who exploit it make it. In the case of this thread, unprompted data leakage of any kind in some of the security environments that the DoD is likely use a Windows PC can be a huge deal. This is less about Microsoft about being malicious (which I agree with you about) and more about general network security.
I just asked the question initially because I wondered if the DoD might have required MS to provide a custom build that might have adhered to a specific security requirement. Modifying a bit of code to honor a DoD contract, even if only a custom patch, is well within the realm of possibility if it means getting the contract or not. Even if they don't require modification, I'm all but certain that MS would be more transparent with them about what type of data that Windows 10 transmits than they would be with the average user.