User blog comment:The Milkman/Alpha and Omega/@comment-166.82.160.118-20121130041918/@comment-1440333-20121130115841

males having the more pronounced crest would make sense based on mating rituals as an evolving species.

As for the inconsistency Nyreen does have a small fringe, as well as more pronounced crests from her mandibles, so Garrus could have meant something like that. Just chalk it up to a turian translation error lol