If a man lets a wolf into your house, that man isn’t trying to “divide you” from the wolf. The man is using the wolf as a weapon against you. You will need to deal with both the wolf and the man in order to survive. There is no future where you and the wolf team up to kill your “true enemy”. If you kill the man first, you are still left with the wolf. And in most cases, the wolf represents the greater immediate threat.

It's getting kinda of abstract, but as a general rule even though the wolf is more individually dangerous, only the man knows how to get more wolves in, and so should always be the priority as long as more wolves remain outside. Not to mention that the wolf is stupid and driven by instinct, and is far more easily used to attack the man than vice versa.

Always dealing with the most immediate threat isn't wise when the man has demonstrated a desire to continue working to create ever more threats whilst you work to deal with the last. Long-term it is less dangerous to tolerate an immediate risk to cut off infinite future risks.