In addition, the thread title wasn't "Was femininity a villain in TOS?" but rather "Is femininity a villain in TOS?"
And suppose the question were,
"Is social climbing villainous in Shakespeare?"
And suppose that one said, "Because we,
today, do not currently feel social climbing is bad, social ambition is not bad in Shakespeare. Iago and Molvovio are just bad apples, from our point of view."
Very few literary scholars would feel comfortable insisting on such a reading of "is" which
excludes
the intended purpose of the artwork,
the cultural milieu in which the artwork was understood,
and how the original audience understood it.
To insist that "is" exclusively means "presently" is to demand that we interpret and evaluate the artwork as we dimly see it through the mists of time. It excludes the sense of "is" which respects the artwork as a point of origin (and the universal message it offers us). To view an artwork as an act of protest, for example, requires that we know what it is protesting against.
Moreover, to ask if there was sexism on Star Trek is rather silly, since it was a television show of its time. Of course, it was sexist.
Madmen has made a living off reminding us that people in the 60's smoked a lot and viewed women differently.
Even if, however, we accept this as the appropriate default interpretation of "is" (i.e., the notion of the timely - what it means to us today - as opposed to the timeless/universal message or original/intended message) in an interpretive question, we would still find that this question is wrong-headed. Why? Because it misreads the code of patriarchy which informs Star Trek TOS. Women weren't villains, but merely slightly weaker creatures with softer (but important) virtues that men needed to protect.