There is no question that User:Marrovi is difficult. The fact that the proposal comes from him makes it hard to take seriously in many respects. And in any event, unless the nahwiki project is really not in valid Nahuatl (of some type or another), I don't see any policy grounds on which you can justify closing this project.  

That having been said, I think you really need to take the comments by Marcos Williamson (by e-mail) and User:Maunus (on-wiki) to heart. It's really too bad that Marrovi's presence muddles the picture so much, because there are apparently some serious issues here.  I am not sure, personally, exactly what to do about it. In theory, I try to encourage the individual Nahuatl test projects at Incubator, but Marrovi is also very active there, and I do not have the language skills to know if he's writing garbage (and can be blocked) or not.

As to the current nah Wikipedia, in principle I like the suggestion by Maunus (that Michael endorsed). But I don't see how that generally fits WMF's rules ("anyone can edit").  I've been wracking my brain over next steps forward, and all I can really see is this:

• Reject and close this current proposal.
• Create a more general RfC page to discuss whether the rules for nahwiki should (or even can) be changed to give more weight to the contributions of true, fluent Nahuatl speakers. I think this should be on Meta, because if it is actually on nahwiki, much will be in Nahuatl, and most of us can't speak it. 
  • When you do this, it would be best if someone had at least a rough proposal in mind. And I suspect it needs to include some content evaluation by experts in Nahuatl who are currently uninvolved in the dispute.
  • Probably someone fairly fluent in Spanish—that's the "major" language that most interested parties speak–needs to draft that proposal and then moderate.
  • Marrovi needs to be strictly limited in his contributions so that he does not continue to write "walls" of text. If you set such limitations, I can enforce them as a sysop.
• See if Wikimedia Mexico can recruit more Nahuatl-speaking contributors.