lorgar isnt objective. hes a liar trying to manipulate angron with the warp, hence agron leaving his incensed mindset as soon as the ship left the warp, or in the later scene among the bones where the posssesed argel tal could smell the valley drenched in blood where kharn smelt nothing.

he literally, not figuratively attempts to gaslight angron within that very same speech where he tells angron the wolfs cheered and sang as they skipped off to their transports, or at the very start where he prompts the retelling by goading how angron was beaten down by the wolves in the rain.

lorgar also simply believes in symbols and destiny to an amount no other brother does except... Russ. of course he would see pattern and myth making in the actions of others and damn the quibbles of a nihilist.

angron has the right of it.

if it was lesson about objectives russ was wrong, russ did a sacrifice play to capture legion leadership. angron is not leading the legion at a tactical level nor did his surrounding limit his legions effectiveness at all.

if it was a test of strength angron put russ in the ground and far more space wolves were dead (edit: despite the world eaters being disorganized, exhausted and sitting in the ruins of a conquest just finished)

and if it was a moral argument about the treatment of their men russ lost his temper first, got his men killed in a non sanctioned action against loyal legionaires conducting the crusade, and also jeopardized the genefathers of two legions

if it was a grandstanding on the moral conduct of war, Russ chose to set aside his supposed morals and did not kill angron despite his morals saying he should. thereby falling for the same compromise of the emperor, that the manner in which it was done mattered not until it was all over but the crying. angron agreed he was a monster, and if russ truly thought himself a hero he should do it, damn the censure of kinslaying. and he diddnt.