Its not just
a mask but a legit death mask made via impression from Sanguinius's barely-cooled corpse, so he was rather understandably pissed off to see them wearing it as if in mockery. And then Dante tells him
why they wear it and he has an "Oh shit, I went too far" moment.
Has the Lion run into G-Man yet so he can snark at him over having finally achieved his dreams of being the Emperor's right-hand administrator?
"Tell me Roboute, having finally achieved your ambitions of ruling in our father's name, is any of it worth it? Have your desires for power, no matter how well-intentioned, brought you the satisfaction in life you have craved? Perhaps you should have stayed a simple soldier like I am still am."
"I think you underestimate what a terrible and pernicious foe the bureaucracy is. I'm starting to think our dear brother Horus may have been more correct about them than either of us is happy admitting."
Speaking of Iron Warrior autism...
View attachment 7836225