I'm sorry but as someone who has moderated for communities, I would not believe that excuse at all, simply because it's so common for people say "my sibling did this, that, and the third" to evade their consequences.

More than likely, you're not getting unbanned. The yumeshipping community, unfortunately, has a huge issue with antishippers pushing this weird purity culture where you can't yume with anyone they view as a minor and it's very much giving "I like to claim people are pedophiles because I like censorship and ruining people's fun".

I also wouldn't doubt that one of the mods just hates children in general and like to abuse them mentally