The telescope in Lorient was not a general scientific instrument for studying the night sky. It had a very practical use: calibrating and synchronizing ships chronometers to terrestrial time.
To accurately measure time, you determine the interval between successive culmination of a star. That is the time when it crosses the Meridian, the line in the sky through the North and South poles. As the time between successive culminations of a star depends only on the rotation of the Earth (and not on its elliptical orbit) it is very regular and can be the basis for very accurate timekeeping.
Ships need accurate chronographs to determine longitude. But the chronographs need to be calibrated, and astronomical observations were used to do that.
But you only need to view the meridian for this application. It probably doesn't matter much if you observe the northerly or southerly meridian. There may have been non-astronomical reasons for having the telescope point North: eg "No window in the south facing part of the building" or "The window in the South holds a gun battery facing the ocean."
So the telescope points north so it can observe the meridian, which is all it needed to do for the specific task that it had.