I signed the legal-link you have posted. I know there are several other folk at Canonical that are keen to help guide and advise as to how to go forward with this. I have been with ubuntuforums for 7 years, am an UbuntuMember and have signed the code of conduct. I am currently admin (team captain) of U+1. Most of my work has been with Ubuntu Development Version Testing and we have a team membership close to 100 users . We test all development cycles that are current. As said before I also maintain the U+1 ubuntu wiki. https://wiki.ubuntu.com/U+1/tester-wiki
We at UDV have been testing unity and other flavors of ubuntu very intently; and unity since it’s inception. During the testing of unity8 we realized there was severe breakage with some core components and when we heard of the decision to discontinue unity8 and close development of unity7 I, for one, was very perplexed as to why such an unique, assistive and accessible DE was being abandoned. So naturally I was curious and inquired of it. It was just natural to brainstorm that the next logical step would be to jump to a unity9 version for amd64 desktop development only. One of the areas of my thinking on this has been the positive social imprint that unity has left on end_users who have chosen to use it over the past 5 years. So , for example, any certain age group has learned the adaptive technologies of the unity GUI. So a group of persons who started using unity at age 55 would be 62 or a group who started at 30 would be 37 and of course a new set of users who started with xenial would not get the full 7 years experience that others have had if it continues to not be reopened for development. Also , as I see it, unity7 DE is probably the best DE to utilize as a testing platform for next development cycles (is why it was wise to include unity7 alongside gnome3 for 17.10 cycle).
Since the beginning of the 17.10 cycle I have been testing unity and decided perhaps I could motivate a group of testers/developers/maintainers to take up the task of maintaining unity7 in the repos (at least). So this in now par for the course. As a lone volunteer contributor it is overwhelming because the project is bigger than any one person. So, my point being is that I am not trying to take over ownership of unity-desktop but, rather just attempting to be a small part of the mosaic.