It can be seen from the general dipole gravity force lines around the rotating spherical mass that the latitude angular dependent force of dipole gravity actually can force the matter around the rotating galaxy toward the equatorial plane.
This means that the matters ejected through the poles by the jet mechanism especially the ones that drift away from the rotation axis can actually come back to the equatorial plane to recycle the whole process again.
Those matters that are on the way of coming back toward the equatorial plane will not be visible because of the lack of the force that can make them stay in the same location for a long enough period of time for the condensation and the gravitation and also because of the significant reduction of the collision cross section between the incoming and outgoing particles off the course from the axis of rotation.
So there is a strong possibility that the dark matters are not only populated around the equatorial plane but also around the whole space surrounding the rotating galactic center like a halo(dark matter halo). They are there but can not be visible. There is an issue of the visibility of the dark matters when they are made of gases and dusts. However, in the jet mechanism, because of its sudden expansion of the volume when they are ejected from the port of the poles, there is a strong chance that the matters will be cooled down quickly and condensed into a much bigger size than gases or dusts.
The force lines in the gravito magnetic concept of dipole gravity makes it a lot clearer on how the matters will behave around the strongly gravitating rotating ultra compact stellar objects.
Due to the point source nature of the active galactic nuclei compared to the sheer size of the volume of the galaxy itself, matters ejected from the ports form a distribution function in such a way that the outgoing flux density is constant, which is the main cause of the flat rotational velocity curves observed in the spiral galaxies.
Of course, this density distribution function is valid only up to the point where the finite boundary of the dark matter halo ends. Naturally, it is expected that the distribution function will be a sharply decreasing function than the typical 1/r as it comes close to the boundary of the dark matter.
Derivation of Lense-Thirring force from Dipole Gravity