Honestly I would rather not risk checking if we can reason our way out of this. Daemon Lorgar built the trap so he would know what questions he cannot answer, find out what they are and deal with the impact later, we have a whole quest because you are right our Lorgar is not a slave to his Mythos so he can change his mind later.
He's not a slave to his Mythos, but I also don't think his Mythos can be readily changed later.
A sub-goal of the Chaos Gods here might be, if they can't win Lorgar over to their side, to damage his potential by getting him to lock his Mythos into an undesirable configuration for us that makes it harder to apply as we want later.
Ah your saying he's missing a few categories on his CK2 options, if I'm understanding the argument correctly. The thing is wouldn't assassination as you've used as an example be in line with the military option? The only difference being only a few people would know. So then the question becomes what are the acceptable ways to conduct these things?
If he for example puts pressure on the planet using the economy then he'd still forcing them and indirectly potentially killing them even if most see it as ethical. Culturally/religiously would risk wiping their people's identity. A show of force which emphasizes that they can't win and forces them to open up just creates future issues.
The only way I can think of to keep his morals and win the scenario is having either so much power or tech a weakness caused by a strategically important planet won't mean much. If this wasn't chaos it'd be a good thought experiment.
The thing is, it's a big galaxy. There are lots of alternative choices, like go two sectors over and use diplomacy to convince a system there to joint up.
Or, when you're a tremendously powerful precognitive demigod allied with an Infernal Exalted predict the potential issue and do something different a decade earlier so you don't get caught up in a situation where you only have two bad choices, and instead you have contingency options.
In some limited scenarios trolley problems exist they're very rare when you Harv the diversity of powers we do.
And I mean that. By the time we get around to conquering planets we'll be able to have, for example, superhumanly intelligent and charismatic shapeshifting mind reading memory eating infiltrators who can turn invisible at will and are near impossible to detect by conventional means. We can then do things like have them kill and replace the leadership of recalcitrant planets in extreme cases like this.
There's also a quite fair argument to make that small polities are rapidly becoming non-viable in this galaxy, and that for their populations to survive the resurgent orks and expanding Rangdan they have to join up.
The problem then is the unreasonable leadership of that polity that refused to accept that reality and instead dragged their people down into the Abyss with them in a futile attempt to retain their own power and privileges.
hmm, if the entire encounter was going to use the Socialize Ability then it was suboptimal to upgrade Close Combat
¯\_(ツ)_/¯
We have another major incoming threat, which is the army of chaos warriors which outnumbers our 'military' ten to one whilst also being individually superior to each of our troops.
A big issue we have is that Daemon Lorgar seems to be making all the running on the Vision Quest. I think the big mistake we made was picking Corax as the other spirit guide. He's been a liability so far as far as I can tell.
And seeing as Corax himself was a poor fit for much of the Great Crusade, he's a very poor fit for helping guide Lorgar develop on a way where he can take part in it. He's similarly enough to Lorgar in ethos that he can't stretch him to develop in ways that help.
We'd have been better off with the Lion, who could inspire our Lorgar to seek greatness.