The thanks list in Blessed also hints at the political direction Vincent tried for a while, notably on 'World of Shit' ("Human shit; untermensch") and allegedly on 'Dawn of the Angry' (purely a rumor but supposedly the original lyric was "white finger on the trigger"). He also tried to get William Pierce into death metal - http://www.natall.com/free-speech/fs007b.html
That's some shaky evidence. You'd do better with interviews from the time. Also, I think it's not clear that "untermensch" refers to anything but an idiot or other useless person.
I never figured out the "a leader from the past who cannot be named." For some reason, I always thought he idolized Caesar. Ignorant, innocent me, I suppose.
Incantation, Infester, Deicide, Malevolent Creation;
Darkthrone, Burzum, Graveland, Mayhem;
If you want PC opinions... metal is not the place!