If we take Rove's interview on Fox News the day after the Page Six item as the best explanation of his view, his basic points are unassailable the state of Clinton's health will play into her decision whether or not to run, she will have to be completely open about the 2012 episode and all of this will be filtered through the fact that she will be 69 if elected and 77 if she serves two terms.
The point about her health being a consideration in her decision-making is almost a tautology. Most everyone assumes that if she feels up for it, she's a go. And if not, she passes.
Even if you take at face value everything we've heard about Clinton's condition in December 2012, it was frighteningly serious. The clot, according to The Washington Post, "can cause permanent brain damage, coma or death if not detected and treated in time."
News accounts say it was caught early, and Clinton is performing as ably as ever. But politicians have a long history of lying through their teeth about their health see Woodrow Wilson, John F. Kennedy and Paul Tsongas, for example. So Clinton will have to provide a full accounting of the 2012 incident and her overall health.
And as for her age, of course it will be an issue. The problem with being an old candidate in American presidential politics is that people use it against you.
U.S. News & World Report had an item in April 2008 titled "Obama Campaign Plans to Hit at McCain's Age." The generational contrast between Obama and McCain didn't have to be made explicitly; it was too self-evident to need much reinforcement, and Obama's theme of hope and change played into it.
The Bill Clinton re-election campaign in 1996 feasted on contrasts between the new and old in its lopsided bout with the septuagenarian Bob Dole. The age issue was so upfront that Time magazine ran a cover asking "Is Dole Too Old for the Job?" and The New York Times ran a thumb-sucker wondering "Is Age-Bashing Any Way to Beat Bob Dole?"
Of course, age is hardly dispositive. Ronald Reagan was the oldest president at age 70 in 1981 and embodied an invigorating optimism despite his years. But age was an issue for him in 1980 and 1984, and a particular threat in the 1980 nomination fight when the speculation, early on, was that he had a light campaign schedule because he couldn't handle anything more rigorous.
Hillary can potentially trump all this with openness about her medical records, and with an energetic and future-oriented campaign, should she run. Her supporters, in the meantime, hope to deflect any questions with cries of ageism and sexism. It will be a nice change of pace to move on from racism as the Democratic rejoinder of choice to other "-isms" neglected during the past eight years.
But Rove is right: Hillary will have to deal with these questions.