Is there any actual confirmation it was Argus still? Because the Denathius version still makes a lot more sense and the role of Argus in this questline seems to be to co-opt the new Arbiter template, without the statement that he was also used to knock out the previous one. Denathrius had the color scheme, he's associated with the drought in quest text and the idea that he'd sucked up enough anima to overload the Arbiter's RAM is at least something that the Bald Man could conceivably plan for, whereas the Argus' mechanics are impossibly contrived.
Pretty much the only plot point made more coherent if it's Argus is explaining why it was so piss-easy for us and the Army of Light to traipse through the Legion's homeworld, by way of Lothraxion and the Legion Dreadlords coordinating to stay out of each other's way. But that aspect is pure fanwank.