Yes, it is questionable that the Retriever has a sense of direction in his abyssal mind. Since his normal mode of action is to planeshift toward its victim, and since planeshift doesn't guarantee arriving near the target, it must have some way to know where to walk to. I'd grant the benefit of the doubt in this case, since all the other problem (impossibility to communicate location with the DMM and said DMM not being personnaly acquainted with the Wizard (or Binky who could be acquainted with the DMM, who is a serious reader of romantic love stories), neither of them can be designated as a target for the retriever...
If by chance a retriever was sent at the Wizard 20 (so the DMM is personnally acquiainted with the wizard, who couldn't have met her outside of the Private Sanctum since she never leaves, so the Wizard 20 knows the place...), and planeshifted near enough the Wizard 20 cottage, he would have cast 2 occurrence of planeshift (one to move to a different plane of existance from the prime, one to get back, relatively near his quarry -- planeshift doesn't let you teleport within the same plane), and therefore... could fight, and subdue the Wizard 20 (who could probably just elect to fail its saving throw on the paralyzing beam). The retriever would then get back to its master... either by walking (so the only inconvenience for the wizard would be to be carried among the village in which his cottage is located for 10 minutes before the retriever disappear) or, in the worst cast, the retriever would stupidly cast his last daily planeshift to leave the material plane for a transitional plane from where he could get back to its master... the next day. So the wizard would have to planeshift back home to the material plane then teleport circle back home. In no case does meeting the retriever and not resisting arrest can result in death. It was designed to bring back its prey alive and unharmed after all.
To the OP: since you mentioned several time that a retriever was sent after the Wizard 20 (who, so far, hasn't taken any hostile action against the Holed Up, Nameless, Hovering, Absent-minded Target (HUN-HAT)), can we establish that the DMM simulacrum and the Wizard are personal acquaintance and therefore the Wizard knows where the sorcerer and the DMM lives, as of post #312?