This is something that bothers about a lot of translators. They do it in anime, too. Why think that "uncle", a strange colloquialism that doesn't even make any sense, is better than just taking the literal translation of "give"?Why do the translators keep using the word "Uncle" for stuff relating to giving up.
I know its commonly used in America where its meaning is used for "i give up", but its not a standard stuff around the world. So, for many new non-american readers, it becomes a lot confusing and odd.