Looking back on his last post here, he said he was indeed working on it, just slowly, since he was in uni/med school and had little to no free time for working on Desolation. He doesn't seem to have logged in since May, but that last post didn't show any sign of wanting to ditch the project, just that he promised an unrealistic date and was really sorry about not being able to meet it, and that he wouldn't be posting much until he had something to show.
I'm gonna keep my belief of 'working slowly and not having a lot of free time'. I'm sure if Caz didn't wanna work on Deso anymore he'd at least log in for a brief 'sorry'. He seemed really touched the fans were still excited for the next update despite his inactivity, after all.