Just playing the odds, I'm almost certain that the base rate of violent behavior in individuals willing to break and enter a home is significantly higher than that in most other populations. Thus, by showing that he/she belongs to the population of individuals willing to break into a home, the intruder is already placed into a much, much higher risk category.
Would I shoot the intruder if he saw me, froze, turned, and ran? No. However, I am going to approach the situation a LOT more cautiously, and my doubt threshold will be significantly lowered. Thus, the amount of uncertainty I'm willing to tolerate before making the assumption that this person means me bodily harm would be much, much lower than it would in many other situations.
In the end, I value my life more than an intruder's simply because I've never, nor would I ever, break into a house. I realize that by doing so, I would lump myself in with the group of individuals who are more likely to commit violent offenses. The only true way we have of judging and being judged is by our actions. If someone breaks into your home, they're accepting that they will be judged by that action.