Hillary and McCain have both already vastly exaggerated their own executive experience out of all proportion to reality, compared to them finding him minimally qualified is not such a stretch.
McCain actually has command experience though. That should weigh in his favor. Neither Obama nor Clinton have ever truly led anything.
It counts for something, but based on my long experience with it, I can't count military command at any level below a multi-star command for an overwhelming amount. Command at company and field grade involves immense amounts of oversight and 'help' from superior commanders who don't want any subordinate's failure to reflect on them, and it operates within a tightly defined set of boundaries outside pure combat ops (which were essentially nonexistent during McCain's career after Viet Nam).
Especially for an academy grad whose dad had the stars, there is a whole network of ring-knockers looking out for a guy like that, who will keep him from being relieved and ensure a successful command tour for him, even if it means finding someone with a brain to stick with the XO job to cover for him. Therefore a successful command tour for one of them doesn't do a thing to help me differentiate the geniuses from the morons, and yes, morons do make it through our service academies, I've met them. I have met some Army cases of hereditary officers who were kept from failing on the record by 'mentors,' so I have a rather jaded outlook on the amount of value an academy grad's service record has.
Not that I'm saying a command tour isn't stressful and demanding, it is all that, but it is not anywhere near the same as being in charge of something that is wholly dependent on your own judgment and skill to keep it from failing, like a business. An intermediate or low-level military command has a whole system up above it that won't
let it fail, a business doesn't.
A governorship is as close as most candidates come to a real test of chief executive ability, because although it's a little more protected than a private business, there are also some considerations in public office which a governor has to deal with proficiently that just don't come into play in the private sector.