User blog comment:D. Cello/Assassinews 03/05 -- ACWiki's Fan Section and AC3 first trailer/@comment-4955322-20120325040541/@comment-1888015-20120328182431

Well, even if the person you're carrying is dead, I guess their body could protect you from a few shots.

The reason I suggested that is because if cover was invincible, it'd take some of the fun out of the series, because you won't be moving as much when it comes to crossing a large battlefield.