It really depends of what Sword's overall goal is. Obviously, with Drake's actions in Onigashima, it's clear some Sword operatives are willing to make alliances with pirates.
One of Luffy's key factors in making Boa like him was not being affected by her Fruit. If Boa tries to seduce Koby with her Fruit, but fails to do so, it could lead to them talking about Luffy.
Boa: "Damn... to think some scrawny, low-ranking Marine is actually surviving against me... So be it. I'll use your own heart against you, then! MERO MERO BEAM!"
Koby: "Oh, no! I've heard about this! Ack!" (closes eyes and holds hands out, then blinks when nothing happens.
Boa: "...GASP! How can such a young man resist me? Are you actually pure of heart, just like my darling, Luffy?"
Koby: "Wait, darling? You know Luffy, too?"
And so a great friendship began.