Doesn't matter. They can still do it to anyone anyway.
> But your logic instagram could just give @kyliejenner to some random person, and you think she would have no recourse?
Well yes. They (Facebook) own the platform, it's a privately owned company and they can do whatever they like either via the ToS or in general. You don't own your account handle. They reserve the right to terminate your account or disable the handle at any time.