Well it is pretty much a who’s bluff is better situation no? The protector will either protect Battler, or somebody else. If they protect Battler, that means a human is definitely gonna live, but the witches will probably strike somebody else because Battler is going to be protected, and therefore ensuring a human death in the process.
Plus, Battler’s ability is not that great, it just gives off trust towards him one by one. And that is not that fast enough. Plus, the possibility of it being a witch tactic still exists. So I would much rather have Battler not protected than somebody else, but I am telling to the protector this:
Flip a coin. If heads, protect him, tails, don’t protect him.