I know this isn't a bug, but I think there was no harm in the obsidian generator to begin with. I would think it no different from a cobblestone generator as far as how it was considered a bug, but those are just my thoughts.
It would make farms hard to happen if you want to have the luxury of seeing your guardian farm. And non-solid blocks might include glowstone, which I wouldn't want them to target me through. I think this should work as it is, and intended.
Confirmed not resolved. Same with carrots for pigs and bunnies.