It has nothing to do with her age! It’s all about her looks! I’m not speculating. The episode is very explicit about this. She can’t leave Talos because if she does she’ll be ugly.
If you want to excise that conversation from your copies of The Cage and The Menagerie and pretend it never happened, good for you. But this thread is about sexist moments in TOS, and that conversation is part of TOS, whether you like it or not.
Feminism started out as women being empowered to make their own life choices for their own reasons. You might not like her reasons or agree with them. But nobody coerced and nobody tried to persuade her to change to meet their own standards. You would impose your standards on her, which to me is the exact opposite of individual empowerment. She had her reasons, you don't like them and think she was wrong for having them and want her to follow your standards. The writers had her make a choice, one that you don't agree with, but it was still a choice. It was her decision, rationally arrived at. Pike doing anything other than agreeing to that decision would have been much more sexist.
It’s not empowering. She doesn’t say “I could rejoin human society and have a fulfilling life, but I’m going to stick around here because I like being kept in a cage and fed illusions.” She says she
can’t go back — she uses the word
can’t three times in this short conversation. Her choice of words indicates the exact opposite of empowerment.
As for Pike, he doesn’t say that he
accepts her decision as the decision of an empowered woman entitled to make her own choices about her own life regardless of what he thinks. What he says is that he
agrees with her stated reason that as an ugly woman she can not rejoin society.
You’re very determined to reject the stated reasons as if the conversation never happened and make up your own reasons having to do with her “very advanced” age (which is never stated in the episode and could be as young as 40). The intended meaning of the conversation is unambiguous, and if you refuse to accept it, I’m wasting my time with you.