Culturally in the "West", male homosexuality is more visible than lesbianism.
For example, if a woman publically shows affection to another woman, it is construed as normal, whereas a man showing affection to another man immediately evokes homosexual connotations.
Dress codes also show a disparity.
If a woman prefers to dress in more "masculine" styles, she will not be seen as lesbian, but as business-minded, but if a man prefers more " feminine" styles of dressing, he will be seen as gay.
I'm drawing upon stereotypes, true, but the gist is male homosexuality is "constructed" socially as more of a "problem" because it is "easier" for males to be seen deviating from constructed norms for males than it is for females to deviate from norms for females.
Even straight men who deviate from prescribed dress codes for males are subjected to questions about their sexuality. Ask any decent "metrosexual".
JW organization's moral codes and literature are far more reflective of and influenced by conservative social construction than the Witnesses would ever care to acknowledge . Hence the more frequent references to male homosexuality than to lesbianism.
Women's relative invisibility in patriarchal religious organizations is the norm - even in JW organization.