Lorgar really came out with some fascinating concepts and some incredible actual heresy along this update. I was not expecting his forces to have captured Tchar of all things, this vote and the discussion honestly do leave me mulling on a lot. As an attempt to organize my thoughts independently:
I don't think binding Tchar is compatible with Angron's direction as a character in the quest, nor is it something that fits an impulse of action on his part as opposed to using the god-killing weapon placed in his hands. I feel ultimately Angron wanting to free Ghreer from the pact and release any other exploitative hold the daemons might have on his comrades supersedes - for what he takes as acceptable conduct - the extremely sensible reservations about killing someone who has otherwise definitely helped Angron's interests even with dubious means of contact. Tchar, and by extension, the Chaos God he is a part of, definitely have a lot on their hands that deserves death, but Angron doesn't know that so despite Lorgar's appeal that is not something that should primarily influence his ability to reflect on the options. Being clever enough to doubt Tchar's benevolene, as he has long been doing and condemn it, in the light of the revelations and what has happened, that should.
On the other hand, I can understand the reasoning for letting Tchar go, and that will by his own words also free Angron and the Chainbreakers of those pacts, even if that is not the primary principle behind the decision. Angron is many things and has done many evils, but I am not sure that as he is trying to be now, he would be up for murdering a currently defenseless individual who he has willingly relied upon as an ally before, as opposed to killing in open battle, on terms that are clearer to Angron's personality. Despite suspecting or knowing that his intentions were always foul. There is something ironic, likely unwise, but also potent, about choosing mercy here after speaking of the creation of a god to be righteous and good in defiance of Chaos and the Emperor alike. No one said that good has to be unwilling to fight and kill, especially against an enemy that gives a face to the malice of the universe, but maybe this is not the way to start it, not the note with which to begin writing the songs of this god. Fighting and killing the Chaos Gods, the Emperor? Angron will be up for that, that doesn't necessarily mean this is the right way to declare war.
In practice, Lorgar's rethoric is attractive, Angron is going through a lot, and he's been placed in a position demanding action and offering a solution to one of his recent woes. Maybe his instinct will speak louder than the nuances of the options... but personally, the more interesting choice here is probably letting Tchar go.
[X] Free Tchar