I am suspicious of this as an explanation. Most straight-identified women I know who will dance with/jokingly flirt with other women are in fact straight and not 'implicitly bisexual'; plenty of them live in environments where there'd be no social cost to being bisexual, and they are introspective enough that 'they are actually just straight and don't interpret those behaviors as sexual/romantic' seems most likely.

Men face higher social penalties for being gay or bisexual (and presumably for being thought to be gay or bisexual) which seems a more likely explanation for why they don't do things that could be perceived as showing romantic interest toward men (like dancing or 'joking' flirting) than that women are borderline bisexual by nature.