When we discussed Cinnamon with Canonical they felt it would be a heavy responsibility to maintain an official version of Ubuntu which used Cinnamon. Linux Mint is not an official Ubuntu (it doesn’t use the official Ubuntu toolchain and distribution mechanism for packages, although that may well be a strength in fact)
We have been told to take down the project AGAIN, so we’re calling it a day anyway.
Maybe when we have some semblance of a functioning NHS digital leadership we might come back to this idea, since (as your post suggests, and many others also do) that there is some appetite for Microsoft alternatives at grass roots level.