Also double-posting lol but tbh by the time I finish typing I expect someone will have posted before me:
The different presentations are also, somewhat significantly, best suited for different things. If we want to try to get ourselves, like, elected Ecclesiarch down the line by making our new school of thought the primary doctrine of the Imperial Cult then, yeah, Philosophy is the way to go. But ultimately I don't think that's wise, one of the major ongoing themes of this, at least thus far, is that the Imperium as a whole has become deeply rotted. And there is no one man, one person, as it stands who can reform the entire thing into something sane and human. Now, can Ignatius become that man? Maybe. Probably yeah honestly. But I don't think that he should and that top-down rework is, at most, tacking on another millennia or two onto something that's already more than half-dead. While conceding ground and issues to would-be allies that would still leave countless to suffer even as we slap duct tape over the cracks.
What I want to see is Ignatius split this sector and maybe a few neighboring ones off into an independent, autonomous domain and make significant reforms at that scale. Where his powers will be more keenly felt, where his presence is more prominent, and where change can be enacted faster and to longer lasting success. Forging a state that can and will survive the inevitable final, catastrophic spiral of the Imperium as a whole when that day comes. And Defiance is very much tailored into that.