Personally, I'm not troubled by the Kirk El Capitan climb. Number one, a 55 year-old guy in the 23rd century would likely be more able compared to someone of our time. Number two, he didn't make it. If he had ascended to the peak, arms raised in victory while a camera-wielding helicopter filmed him while flying around him in a circle, yeah, that would've been pretty silly (though I can imagine Jerry Goldsmith would've provided excellent music to the moment, though
). As it is, he slipped and fell. And McCoy chided him about performing crazy stunts. So all in all, I can buy it as presented.
