So after completing this week's quest, Eris tells us that Calus his being forced to act this way. If you find and listen to the Calus bot in this week's mission. Rather than trying to stall or convince us to join him, he seem more concerned that we are wasting time and not rushing to help Caiatl. Together these 2 things make me think that deep down Calus does not agree with the Witness, and the only part of him able to resist the Witnesses control is his love for Caiatl. This would explain why Calus's nightmare was Caiatl and why he repressed his memory's of her, because she is his weakness in the eyes of the Witness. This would also explain why Calus tried so hard to lure Caiatl to him. Sure he claimed its to corrupt her but he also wants us to save her. Side note: I'd also like to point out that the events of this season start to fill in blanks and possibly lead to the events that we saw in the dark future lore book. In it we saw Mara Sov in control of the Leviathan and leading cabal forces. So it's possible the point of this season is Calus wants us to have the leviathan as it's the only ship large enough to fairy all humans, cabal, and fallen off earth once the Witness arrives in lightfall. It's also capable of interstellar travel, which the humans lack and our allies probably aren't able to due to lack of resources.