MTG - Kicked Blood Tribute+Sanguine Bond vs. Reinforced Bulwark.?

Remember that there's a difference between dealing damage and losing life. Being dealt damage results in that much life being lost, but losing life doesn't necessarily mean damage was dealt. Since Sanguine Bond just says "loses life", not "deals damage", that means no damage is dealt, so the Bulwark can't do anything to prevent it.