LT would certainly protect Vlad's soul from being snacked on by a morganti pointy-stick, but I can't see anything to keep them from sticking a knife in his back and hiding him for 3 days. Which brings to mind a question previously discussed here: What happens when the owner's soul is absorbed into the GW for protection for more than 3 days? Does he/she return as undead? Is the body simply unable to reabsorb the soul? Does it matter at all, since the 3 day limit has to do with "departure of the soul", which becomes a non-issue? They could always find a way to lure him to deathsgate again. I can see him going in order to save someone important, even if it meant incurring the wrath of the LoJ.