This is creative writing, where effect matters:
There is no main verb in that sentence, but it is written as if it were a sentence.Just, plain, black.
Fiction is often careless about grammar. However, you can use the present when narrating past events- it's acceptable and common in fiction and is called the historical present. Writing is about creating effects, making people feel or think and not about following prescriptive grammar rules slavishly to the detriment of the text, so I would agree with some of the people on your site. Shakespeare, Dickens, Austin, etc, all broke the rules of grammar frequently. If the present feels and reads better, use it.
PS The link doesn't take me to your text.
Student or Learner