The quasar is not shining through "the core" of the galaxy. Photos typically over-expose bright portions of the disk; the "core" is far smaller than is apparent in typical photographs.
Go to
this photo of Stephen's Quintet, and look at NGC 7319 in the upper left corner. This photo is less over-exposed than many. Notice the small, circular area in the center of the galaxy? That's the maximum extent of the truly dense "core" of the galaxy (and is likely over-estimating). The opaque portion of a typical spiral galaxy is really quite small in relation to the total disk. In this photo, I think the quasar is barely visible directly beneath the core, if you know where to look, but it's hard to tell. At any rate, comparing to other photographs, it's easy to tell it is well clear of the densest part of the core.
Nor is the galaxy either far away nor massive enough to produce gravitational lensing, so we should not expect to see lensing here.
There's no problem.
Added by edit: Looking around for this, I've noticed several other quasars sighted "on" galaxy images, and it seems
in every case the quasars show absorption lines in their spectra consistent with their light passing
through the galaxy in question (e.g. NGC891, NGC4203). They're never
in front of the galaxy. Again, based on this information alone, one could still say they are
in galaxies, but we have plenty of other reasons to say they are more distant.
Edited by Zhimbo, : No reason given.
Edited by Zhimbo, : No reason given.