I'm not sure why you're trying to do that.
Windows 7 cannot run Hyper-V. You can install the Hyper-V Manager on Windows 7, but that only requires Pro or Ultimate. [1]
Client Hyper-V was only added in Windows 8, and you only need Pro. [2]
[1] https://social.technet.microsoft.com/Forums/en-US/f0f1dc3d-9...
[2] https://blogs.msdn.microsoft.com/b8/2011/09/07/bringing-hype...
Oh. Then I agree with you that Microsoft screwed up the licensing -- but it's a different screw-up.
Windows 7 Ultimate is just like Windows 7 Enterprise, except for the virtualization rights. With Enterprise, each license allows 4 concurrent VMs. With Ultimate, you only get one.
The original idea of Ultimate was to be a consumer version of Enterprise. You didn't have to go through a salesman. You could just buy Ultimate on Newegg or Amazon.
However, Microsoft crippled Ultimate by putting in the 1-VM restriction. Considering how much Ultimate cost, this was a really cheap move on Microsoft's part.