You're not gonna do other Sephiroth fields? Like Sephiroth with book and with sword?
That is actually very easy to do is well. Since he already made a model for sephiroth, it comes down to renaming the model parts for the sephiroth he made to the model parts of those sephiroths, and replace them. It's brainless work that he doesn't need to spend his time on. He should just continue making new stuff so if (when really) his life becomes too busy or he loses interest you'll have all or as much of the assets to finish the project yourself.
For example:
He would need to complete these or we'd end up using PRP for these models instead -
Cloud - 13 Years Old (enab)
Cloud - 8 Years Old (buge)
Cloud - Soldier (ekbf)
Cloud - Soldier Helmet (eihd)
Cloud - Woman (dlfb)
But these would be easy enough to complete without him since they are identical -
Cloud - Wheel Chair (htje)
Cloud - Bike (brib)
Cloud - Parachute (afie)