It is active and maintained. I wonder if you looked at one of the other repos the ZorinGroup has (They have more than one.)
Here is the current Zorin Repo and if you browse the packages, you will find additions and uploaded content quite recently:
https://launchpad.net/~zorinos/+archive/ubuntu/stable
That being said; the regressions in the kernel in question are due to the Kernel development team, not the ZorinGroup. Zorin OS uses the provided kernel, but does not develop it. Reporting to the Ubuntu Team really is bringing it to the proper doorstep.