Yeah, the story is telling us that Ballas can hack arbitrary Sentients, which puts his careful maneuvering to allow their creation into a new light. It also means that Ballas is now a master manipulator who has been orchestrating literally everything flawlessly up until this point. It makes you need to reconcile that level of mastery and self-control and willingness to sacrifice and self-abase with, well, what we got.
If a story wants to get away with a master manipulator who lies and deceives in all of their performances, then you need a way to either tell the reader who they really are, or you need for the reader to look back and realize the double-meanings in what was done. Ballas was monstrously arrogant, and then he was humbled, forced into a malformed body, literally collared and leashed. At no point do we see examination of this in New War. It's like the story forgets that there was a pre-NW Ballas wearing what he presumably considered the ideal body (since he was a high-ranking Orokin and could literally take his pick). Now, if Ballas was actually planning everything and planned to use his mind control mojo on all of the Sentients, and his entire reason for kicking off the Sacrifice arc was to get himself 'captured' and 'converted' by the Natah he already mind-controlled, we could get at least a lead into what we got, but we had no foreshadowing of that. At best, we had the possibility of him slipping the literal leash the Sentients had placed around his neck.
And, the more I think about it, the more I feel in agreement with the theory I read elsewhere, that the story was originally written with the third-act roles of Ballas and Erra swapped. Erra was supposed to be the big bad. Erra was the one we first saw fucking around with the Veil, and building heat on himself by killing Teshin (which, again, went nowhere and soured me hard on the quest as well). I can absolutely see the quest meaning to have us meet up with Ballas when we break into the sun-crusher, handing him the Paracesis, and engaging in actual retrospective about the parallels between him and Umbra before getting a very imperfect-but-deserved death that let you move forward.
And another point: What the fuck were the actual rank-and-file Sentients thinking during all of this? The great thing about the Sentients, in their previous lore, is that they are completely distinct from the other factions in that they are all individuals. The Grineer are commanded by the Queens, the Corpus by their Board and devotion to their ideals, the Infested have a hive-mind, and the Orokin of old mind-controlled everyone they could get their hands on in a variety of ways, but the Sentients were (pre-NW) immune to that control, and that is why they were a threat. Every Sentient you fight is a Sentient that is or was willing to terminate their own line and burn out their own capacity for reproduction in order to face a deadly foe, one which they believe will come for them on their new home.
If I were telling New War, I'd make it explicit that the Sentient were not really hierarchical, and that most of the invading Sentient, upon utterly wrecking the factions of the Origin System, decided that their original plan to fight at great struggle and sacrifice to Sol and all die in the process of killing the Origin system at its literal root was massively overkill, and not being the mindless monsters that the Orokin believed them to be, settle instead for setting up Narmer to ensure that nothing like the old Orokin empire could ever rise again. We'd see more interplay between Erra and Ballas, and make it clear that Erra was indeed using Ballas to help set it up and probably relying on his knowledge of void bullshit for part of it, and the point would be that while Ballas would be using Erra to set up his cult, Erra would be using Ballas to set up a stupid self-sabotaging cult that would fail, specifically so he could convince enough Sentients to fire up the sun-crusher and go back to Plan A, since containment had failed.
But regardless, I don't think that NW did it for me. I don't see how the interpretations of Ballas having control of Lotus from the start of Sacrifice onwards meshes either with his actions and words there, or with the fact that he could totally just take that Lotus, a few Orbiters' worth of space-cocaine, and ride off into the sunset with her, declaring general victory and letting the incoming Sentients burn everything to the ground. Hell, I don't know why he was doing what he was doing in the weird intro in the first place, other than "I must kill this person in front of this other person, because that is what the script says!"
Also, since the question was asked, I went with Margulis as my chosen name, since Natah's the persona who thought giving Ballas a sexy new ass was a great idea and exposure to Wally-bullshit has a bad, bad track record in terms of long-term mental stability based on us, Rell, and Grandpa Al. Margulis, conversely, liked the Tenno and thought keeping them around is a good idea, so I'll happily take that persona, and was delighted to get the opportunity to give Lotus back the helmet I'd been hanging onto for her.