Non-expert readers could be forgiven for reading that and thinking this is some sort of "discovery" ("Hubble observes something new and unusual!"), that the forbidden emission lines only appear in Type 2 Seyfert galaxies ("The spectral lines that Type-2 Seyfert galaxies emit are associated with specific 'forbidden' emission lines."), and that they only come from the active nucleus ("in the midst of an incredibly energetic galactic core"). But none of that is true.
Forbidden emission lines are ubiquitous in astronomy. Any time you see an object with emission lines, some of the emission will be forbidden. So we see forbidden emission lines from Seyfert 2 nuclei, from Seyfert 1 nuclei, from quasars, from non-Seyfert nuclei, from the nebula of star-forming regions, from planetary nebulae, from supernova remnants...
You could pick literally any spiral galaxy that Hubble has observed and title the image "Hubble sights a galaxy with 'forbidden light'", and the title would be just as correct. Or swap "nebula" for "galaxy" and use any Hubble image of a nebula in our own galaxy. (There's even forbidden emission coming from the solar corona.)