User blog comment:Zack Tan/Volume 7 Intermission/@comment-138.162.0.41-20150903140211/@comment-138.162.0.41-20150904150109

If PDL can learn that Momon = Ainz, that means he can link the connection between Shalltear and Nazarick. Momon gained fame after defeating the supower powerful vampire in the forest... which I'm sure PDL can deduce was the vampire he fought with the armor. There also the whole Momon vs Jaldabaoth thing... and also when Momon challenged Albedo.

If PDL knows Momon is a fraud and just Ainz, he could undo the attempt by Ainz to make Momon a heroic figure.

Also it would give PDL insight that Nazarick is more than just a few people (like the Thirteen Hero invasion), and is basically an army (like the Greed King invasion). That let's him tailor the scale of his plans from something small to needing something MUCH larger.

PDL learning that Momon = Ainz is just plain bad news for Ainz.

The greatest mistake PDL could make, is while recruiting support to defeat Nazarick, is asking Momon to help him. NOT knowing Momon is Ainz is a massive danger to PDL, seeing how he wants to keep off of Nazarick's radar for as long as possible.