Nami thought of Bell-mere when she saw Tashigi, and she made a no-homo joke about Kalifa. If you re-read that fight, Nami shows zero physical attraction to Kalifa and even rips up her clothes without showing any reaction (while Franky does react). Nami just made a joke about Kalifa being a sexy secretary and then said she sounds like an old man; she didn't get horny at all, much less as horny as Sanji.
On the other hand, Nami has blushed when holding Luffy's head to her chest and when seeing him get "kissed" by Reiju. She's also flirted with men in the past and the only big display of attraction she's had is towards money, so this lesbian thing is bullshit lol. As if Oda would make any member of the main cast LGBT.