Probably just off the project. It is the best explanation for why no new artworks have been done over the last months. I think a year might have passed
He was reported to be out of action in june. I might be wrong on this one, but i think they said that he was adding some details to a few things in march-may, so that's the last time we have heard of him drawing things.
Even that is a bit vague, since the quest after 0.14 was supposed to be a bad end story for Vehlis, for the 3 players who didn't forget to intentionally mess up her story line 2 years ago. I think i remember them saying that they were adding something for the rest of us too, but i do recall that both the bad end quest and the additional content were indicated to have focused on reusable art.
But if you want to look at it that way, the last content we got that Nomo has directly worked on was the 0.14 release in 9. february (public on 17. february), so that has been a year indeed.
Ironically, that post ends with the iconic:
" It will be a smaller quest than this one, so we hope to have it out on a faster cycle than this one. "