I wouldn't consider walking, or even running away surrender necessarily. Of course, we're talking in kind of general terms here, and situations are always more complicated and surprising than we imagine.
Still- if it's just me, getting pushed around, or having a punch thrown at me, I think just escaping is a valid option. It seems like trying to do technique could become a surrender in itself: to trying to win in a conflict, or trying to prove courage, or whatever. Not that the idea of running away from a fight doesn't bother me a little, it does, I'd probably feel like I lost if I ran. But I think that feeling of having lost is probably not so good, and counter to the idea of not inflicting damage.
I'd like to hear from people who have ended up being faced with the decision to use technique or walk away... I think one possible problem with this discussion is that you probably don't have much time to think things out when you're being confronted violently.