You're good!I especially appreciate the way in which you pull together several scripture passages which present similar challenges. Let's stipulate that you clearly cover one of the standard interpretations. As you know well, it's an option articulated by a number of Christian interpreters.
Jesus certainly was not always polite. He could be, and often was, blunt. In addition, I would add he strikes me as having been a realist with regard to human nature in practice--some will listen and accept, others will not--so what's a disciple to do? We've already discussed our differences over judgement/discernment and judgmental.
Both of us know "dogs" and "swine" are not to be taken literally but instead as powerful metaphors. Whatever Jesus might have in mind, neither term was complimentary in his culture. Both of us are aware of the debates over the place of "the gentile mission" in Jesus' mind. We differ over how this passage might apply to the matter. You focus on the question of Jesus' attitude toward gentiles; I focus on the passage's possible application to the work of those who took Christianity to the gentiles and some first century Jews. Strange and interesting, isn't it, how the two of us look at the same words yet ask different questions of them?
Several factors seem to me to be in play and to fuel our different responses to the passage. The first relates to how each of us chooses to deal with the "rough" aspect of the passage. Let's face it. I sometimes take understatement past all reasonable limits. When I briefly wrote of the passage's harshness and the like, I automatically "felt" as if I had said a great deal. What you took to be an effort to "clean up" the passage did not feel that way to me. That's a mistake on my part, by the way. I assumed too much on the part of potential readers and should have taken more space to unpack the terms.
Second, it's probably impossible for me not to interpet a scripture passage without taking into account most of 20 centuries of interpretive work in the Christian community(ies). The long tradition no doubt affects me in ways of which I both aware and unaware. One feature of that tradition is a tendency to apply scripture passages to one's own slice of life--hence, the pastoral life story.
Third, it seems to me both of us may be reacting to Christian sterotypes of Jesus we encounter. We've discussed one or more of these in recent posts. In this particular case, I deal often with people who believe Jesus (or a disciple of Jesus)could never "move on" from anyone in order to deal with someone else more open to Jesus' teachings or potential lordship--hence my tendency to read and apply the proverb the way I did in my posting.
Reading back over the preceding paragraphs, plus your post, I have no difficulty understanding why so many trees have had to die that endless commentaries might be written!