There's a lot of hate for Trans people, and when it comes to kids, it's a minefield as far as ethics go.
My point of view: Part of growing up is being happy in your own body and learning how to use it to its fullest. People who don't know how to be satisfied with what they are born with don't ever really grow up and experience the joy of just being alive to its fullest. Being young is critical to HRT treatments being effective, but most children aren't fully developed enough to make such a life-altering decision at such a young age. Hence, adults need to take over to make that decision for them. If they later regret their choices, they'll have someone directly to blame for encouraging their transition at such a young age. Again, some people transition and go through surgeries and are perfectly happy, but the statistics don't lie about how uncertain that outcome is.
tl;dr hug and befriend trans people.