>>529456694
They say they're LIKE siblings. Not siblings.
This is an important distinction.

The same terms are used to describe Silver/Blaze's relationship and Shadow/Maria's relationship in JP. Almost nobody attempts to argue that Silver and Blaze are brother and sister, and that shipping them is morally wrong.
弟のような - Otōto no yōna
兄妹のような - kyōdai no yōna
no yōna - like/similar to
Meaning, it describes a dynamic, not literal. If it was literal they would not use no yōna.

They're a special case that people, especially in the West, struggle to wrap their minds around. Because Sonicfags are autistic and don't know what nuance is.
The dynamic of lover, friend, and family all exist simultaneously when it comes to Shadow and Maria.
Not any one interpretation is explicitly wrong, but only one cannot encompass everything they meant to each other. They will and do die for each other, because without one another, a piece of their heart is permanently ripped away.

The Japanese are fairly non-literal. But when it's translated to English, English fans will take it as literal.
Think of their relationship with no label except "everything". That's what they were to each other.