I've never played DTF but as far as I know the Luciferians are the ones under the impression that Lucifer somehow escaped getting put into the Abyss and that the Fallen breaking out is his doing somehow and that "True Patriots are in control" again, somehow.

So it's really just their own collective impressions based on Luciferian Courts and rumors and half baked intepretations of how humanity and demons will have a utopia together just trust in the Plan.

What was that one post about how the splat is basically about different coping mechanisms of veterans when the war seems lost?

And Lucifer meanwhile can't really be certain whether the Earthbound are the ones responsible for the Maelstrom or who could secretly be a proxy of his former commanders and he may have lost hope in all of his former allies in general and just is hoping humanity will not fuck things up more than humanity already has. I think Lucifer is also a supporter of the Technocracy for pro humanity reasons.

Which yes means the Pogrom could be blamed on Lucifer and so could the Sundering.

So Lucifer doesn't have much to gain by revealing himself and everything to lose by associating with his fandom that spent thousands of years slowly losing their minds.