Incest in real life is immoral and wrong because it’s harmful, so it’s wrong to ship two real life brothers.
On the other hand, fictional characters cannot take damage. They are not living or tangible beings. They were only made for us to have fun with, so there’s no harm in shipping them in a romantic context, as long as you’re a person aware that incest in real life is and always will be wrong.
Also, literature and other art forms have always found forbidden subjects appealing, especially in romance. Certain forbidden love tropes (such as incest) gain attention from viewers who have grown bored with romance stories where there aren’t as many problems or messes.
It’s okay to ship fictional brothers, because at the end of the day it’s just that: fiction. And no one in real life will be hurt by it unless someone with the intent to hurt gets involved.
And it’s normal to feel uncomfortable or disgusted by these stories, since everyone has different likes and dislikes. No one should be forced to consume material that makes them uncomfortable.
