Sabrina wasn't trying to change your opinions, and it almost sounds as if you're saying that she needs your approval to use any of the names she loves.
Anyways,
Brook and
Lyn were origionally boys names, so there is no reason
Brooklyn shouldn't be used on a boy. Just because it's listed on BtN as being feminine, and it's usage is mainly feminine, doesn't mean that it must be confined to only girls. What about the over-usage of
Madison,
Evan,
Ryan, and
Taylor on girls? Are they not boys names?