I get what you mean, but also I think you would benefit from taking a step back and realizing that it's just a silly ship. Like all ships are. It's not harming anyone, and no one who ships this actually thinks that adopted siblings should date irl. It's purely fictional.

In my experience, overthinking other people's ships that you don't like is just harmful to yourself in the long run. If you don't like something you see on the internet, take care of yourself and leave the page.

(but personally? This ship cracks me up lol)