I think that he should probably eventually get more people to him, but I can emphasize with him with not knowing who to trust with a huge project like this mod.
What I believe that he should do is if possible, to get in touch with Tolkien scholars or even maybe the Tolkien Estate itself. I believe that he should do this if he ever needs a second pair of eyes (not including the other modders who work on the mod with him) to critique additions before updates. Also, if he is able to do this, he could possibly get clarification on the more confusing and ambiguous aspects of Tolkien’s universe.
Even if he is not able to do any of this, I am always stunned with shock and awe with every update he releases blowing me away! This is literally the biggest Minecraft mod of all time and yet it is so obscure compared to the more popular mods, and that is considering the fact that this is one of the only mods that I use, though recently I have been branching out. The obscurity of the mod reminds me of The Lord of The Rings Online and its obscurity among the mmorpg genre.
I may have my own issues with the mod, but the sheer amount of work and depth that is put into it outweighs it all!