Dan said:Oh he still has a moral compass, it's just a completely fucked up one.
Think about it: Would you yourself, when you know people are gunning for you, go back into your own house by yourself and possibly be gunned down or would you see what happens if you sent an innocent person in.
Answer this honestly and put yourself in Walts shoes. Don't go "DERP HE'S STILL A TERRIBLE PERSON AND WAS GOING TO GET THAT OLD WOMAN WACKED." Yes, that may have been possible, but he was checking to see if his ass was going to get wacked in return.
Walt is shades of grey. He's not a good person, but he isn't a bad person either and if you think about it in his perspective and within the shows writing rules/rails, you'd probably do the same thing in the situation.