The Omicron existential crisis was around losing track of their sense of self through an endless series of augmentations. It was the opposite of most conquering empires - they had no sense of ego or 'self' strong enough to give them purpose and push them onwards to further conquests, which eventually pulled their society into a standstill. There was no mission. They desired no legacy. They had nothing to prove.

This sort of setup could always be exploited to turn them against us, but I'm sure that Omega would have something to say about that.