I'm no astrophysicist but shouldn't a galactic anchor supermassive black hole tearing ass through it's soon-to-be former host galaxy be dragging a fair amount of material with it and creating a bow shock, much as this runaway star is doing?
What do you think is generating the x-rays they're using to spot the black hole?
I believe the X-Ray source may be a foreground or background object not associated with the galaxy, and possibly stationary as well. I would expect a super-massive black hole capable of anchoring an entire galaxy that is so off-center would cause some serious deformation to the host galaxy, which is a feature that clearly is not present in the provided image. I also believe the lack of an X-Ray source at the galactic nucleus is not due to the super-massive black hole being removed, but rather simply that the super-massive black hole that is there is not currently "eating" anything and thus is not producing prodigious amounts of X-Rays.
I find you lack of faith in the forth dithturbing. - Darse ("Darth") Vader