Making something abnormal seem normal?

Solution 1:

Maybe detached? This has a connotation of emotional coldness or numbness

adj. impartial or objective; disinterested; unbiased; not involved or concerned; aloof.

It fits best with your first sentence:

The writer's description of the scene is detached.

I might also suggest something in the vein of nonchalant, which fits a bit better with more of your sentences.

adj. relaxed and calm in a way that shows that you do not care or are not worried about anything

The writer's decription of the scene is nonchalant.

The writer describes the scene nonchalantly.

Solution 2:

You should consider trivial/trivialize (UK trivialise).

The writer's description of the scene is trivial.

The writer trivializes the scene.

This disgusting scene is trivialized by the writer.

M-W:

trivial adjective

1 : commonplace, ordinary

Compared to her problems, our problems seem trivial.

trivialize transitive verb trivialized trivializing

: to make trivial : reduce to triviality

The news story trivialized the problem.

Solution 3:

Since you explicitly mention that you don't know if it was a verb or an adjective I think you will fare best with makes the scene seem adjective or describes the scene as adjective. The reason is that the effect of a scene seeming normal in any given context is likely conveyed by the persons reacting unexcited and without the disgust the reader feels.

Just picking a few adjectives from the synonym list of commonplace here, ordinary, unremarkable, conventional, typical, everyday...

The writer makes the scene seem ordinary.

The writer's describes the scene as commonplace.

This disgusting scene is skilfully made to seem unremarkable.

This is on the assumption that the scene's sense of normalcy is brought forth by it being an everyday thing for the participating persons. If you are trying to describe a writer that wants the reader to think that the scene is normal in our world that would be different there is more likely a verb out there that fits that description because it's an Inception level fewer.