It is simple. Vampirism heals. Healing can remove bleed. Thats it.
no, that's not where the ruling came from. basically, my opponent had vampiric creatures out. I asked shadow if deathlock prevented vampirism. He said no, because while it heals it's not counted as healing so it gets around finite life. Which is why I then chose to not play the deathlock and played something else instead. Then the Warlock played 2 Heal spells in one turn recovering a bunch of damage. He would have been dead the next turn had he not healed and I played the deathlock.