Despite being first in Legitimacy score by a significant margin, I've lost the race to Tier 1 Legitimacy Groups as all 4 SSD heroes have already been integrated.

The reason, I can imagine, is the fact that the AI keeps conquering and losing planets every 10 seconds, thus getting far more opportunities for integration, while I actually try to hold onto my possessions, develop them and enjoy the ride.
This means that I will no longer receive any integration offer from other groups (Tier II and downwards), is that right?

This is so disappointing that I'm thinking of abandoning my campaign... Integrating minor warlords add a lot of spice to the game, and Palpatine is still far ahead in the future as every single Imperial faction is a superpower in my game - the only exception being Eriadu who are on the other side of the galaxy... I'm the PA.