No offence but as long as you give him credit where credit is due why couldn't you release the Age (or even "finish" it depending on what needed to be done)? I mean I have experience before with working diligently with people and then they dissappear often due to no fault of their own and sometimes they just don't come back. I personally believe there could only four real possiblilities that could happen if you did release the Age now.
1. He would be pleased that his dream was so loved that it continued in his absense.
2. He would be annoyed that he didn't get to make the initial release but be happy people are enjoying it.
3. Ask that it be taken down so he could have it finished.
4. Be angry and ask for it to be taken down perminately. (Which isn't much different than the state it is now except it wouldn't have been enjoyed at all.
I know you are trying to do the right thing and I respect that as I'm sure everyone else does and in the end it is up to you. It would just be sad to see this Age go to waste.