So, he didn't view it, I guess.

It does feel more like Sci-Fi for me

It's definitely more than a horror project. But, it's also definitely still horror.

Creator of work of art announces everyone has been experiencing it the wrong way, and their own views on what it should be makes it less enjoyable to the wider audience.

Name for this trope?

JK-Rowlingify?

That being said he's definitely not approaching her level with this statement and I even see what he means; its a movie about mental health, on some level. And struggle against the modern world.

But uh.. it is a horror movie ;P

I can see that, it's more creepy than scary, and having a few scary scenes don't automatically qualify a movie as horror.