In addition to her historical feats, she is also Izo’s sister, one of Whitebeard’s commanders. She is the first transgender character introduced in One Piece.
Marco, known as the phoenix in the One Piece series, had his closest confidant in Whitebeard, the captain of the Whitebeard Pirates. As Whitebeard's right-hand man, Marco was deeply trusted and assumed leadership of the crew after Whitebeard's demise.
Honestly, I wouldn't mind it, provided that the character didn't show any hints of leaning toward a specific sexuality already. For example, I would find it very odd if Sanji was revealed to be gay, since one of his character traits is that he loves ladies.
While One Piece is one of the pioneers of LGBTQ+ representation in anime, it is still not perfect. The series has turned to stereotypes when discussing these topics in the past, like the Okama, a group of assigned male-at-birth characters who do not comply with the gender binary.