Doesn't the Bosmer only become cannibal when at war and in their "burial" ceremonies?
No. They eat only meat, and biggest of all they eat what they kill (all of it and anything). This is why when they go to war they fast for a few days, and try not to engage in war that much (they'd burst). Also, they don't touch bodies that have been dead for over 3 days
If one kills an altmer, they're going to eat it. If they kill another bosmer, they will eat that bosmer. Of course, the family of the hunter that killed the thing can also dine on the body.