Blowing up Rykad Minoris and obliterating the women and children of the genestealer cult are the two dogmatic choices that are just factually correct even if you're iconoclast.

But an opposite case also exists. Not triggering the warp incursion into Gomorrah is an iconoclast choice that just makes sense regardless of your alignment, because chaos is still the larger, longer term enemy and feeding a ton of souls to Slaanesh is worse than killing a few thousand drukhari.Everyone wants to kill them because of what they did to you and your people, but if cooler heads prevail then you remember that chaos is worse than deldar.

Don't worry, if you choose the right options in Marz's companion questline, you get thousands of deldar killed in a civil war anyway, so you get your revenge.

This long con has actually paid off. If you kill marz early, you don't get to kill all these guys. This was the dracon of the black heart, which is pretty high up there. You also cause the reaving tempest loyalists to break off from the black heart and start a rebellion, but then if you murder Marz *after* he gives that order, then you just start a mini civil war between two kabals with no actual point.

Sometimes it pays to be patient. Many, many more xenos are dying as a result of our patience, including a great many that we would never have been able to reach in Gomorragh. Shooting everything you see has its merits, but sometimes cleverness serves the Emperor better.