Isn't the lesson to use the best people regardless of gender? In which case, why should she go instead of someone more qualified?
When she was tested, there weren't many that were more qualified. She should have been part of the Mercury 7.
Sending her now, well, it wouldn't make sense in a role more suited for someone younger, but if she could be sent as part of aging research, like John Glenn was, then that'd be great. But mostly the article laments that a great talent was denied something she'd have been perfect for because of stupid sexist notions from the 1950s.