I vaguely remember that he was supposed to invade the other RKs to free the Slavs cause he considered them Aryan. It would have been really fun to do that.
Slight rewrite of TNO Lore:
With the rise of the West Russian Front or whatever the fuck the successor to the Soviet Union in the 50s was, German officials in the RKs begin to get concerned about partisan uprisings seeing revived Soviets as the lesser evil. Hitler authorizes Rosenberg to do some reforms (But not all) and even the reforms Rosenberg does do prove to be stymied by SS and his Nazi peers who refuse to do any compromise.
This fucks up Rosenberg's political career throughout the rest of the 50s and he is effectively sidelined with only minor honorary roles in government. The West Russian war ends inconclusively meaning there is no reason to give Slavs rights, but the communists are still a potential threat on the border, as Western Russia isn't as splintered up in as it is in TNO
Come the GCW and Hitler's death. He aligns with either Speer or the military through pragmatism and wanting to push his own reforms. Preferably the military because then you get two separate 'reform' paths (And preferably one that isn't basically a trap path) for Germany. I don't count Bormann since even if you do everything correct you get railroaded into disaster anyways.
If he is made Fuhrer by the military after victory as a way to legitimize their authority, seeing as he is an original proponent of the ideology, he can begin to enact political reforms that the military regime likes, since the military faction that takes power is different from Bormann's clique and is run by the more neutral 'realists' in the military who see the present situation as untenable.
These reforms include solving the situation of the RKs being both military and economic blackholes by negotiating and propping up friendly, or as closely aligned as possible, native-run governments with German oversight relegated to military protection. Slavs get basic rights in their own states and autonomy, while German overlordship is retained, effectively pacifying Eastern Europe for the most part, although in some areas like Russia this is basically impossible as they will never Trust the Germans, meaning that RKs remain there as holdouts or the Rosenberg government simply funds and backs 'friendly' Russia states (See Vlasov, the Tsar, etc. who exist in current TNO lore as splinter states from West Russia) and effectively cede most of RK Moskowien to one of those figures in an attempt to stem off Russian invasion, although obviously these countries have scores to settle with Germany as well.
It would actually make for a fun stupid ass minigame between Rosenberg, Orthodox Nazis in the RK, remaining militants, Speerite reformers, his military clique, and the fucking SS; but of course having fun and interesting paths for Germany in TNO is verboten because the whole mod is a morality tale that Nazis are bad, as if everyone in the world doesn't know that.