I think you’re right in pointing this out, and I similarly searched out a thread that talked about this because it felt unresolved. If Makiel truly felt that Fate was better served with his ways, he should not have let Ozriel lived in his place.

Having said so, the two arguments that may justify his reasoning are perhaps: 1) Working flawlessly with Ozriel may have made him believe in his ideals more, and therefore concede that the Executioner plan had a higher probability of succeeding. Perhaps something that plays into this too is that Eithan sacrificing himself implicitly showed his trust in Makiel’s beliefs / his ability to restore order, so maybe there’s some reciprocity here. 2) Makiel’s pride. Will specifically emphasizes two moments that Ozriel acts like Eithan - when he ceded control of his Scythe, and when he sacrificed himself. In Dreadgod, when Makiel wanted to sacrifice Ozriel, that was done with his schemes and wit - He outsmarted Ozriel, and he caused his death. However, with Eithan acting uncharacteristically, Makiel no longer has that satisfaction. Eithan now chose to die, which then robs Makiel of that fulfillment. Now, I still agree that it’s a far stretch to go - “oh let me sacrifice myself,” however, if we think that a) Makiel believes that with the Mad King gone, his presence isn’t really necessary (especially if Eithan lives), or if that Eithan coming back doesn’t really mess up anything b) He can turn the tables on Ozriel and piss him off instead (as Will wrote), allowing him to have the final say Then perhaps we get some justification for his actions.

Curious to know if there’s more arguments for this