How irresponsible was McCain for picking Palin in 2008 ?

The "depth" of Sarah Palin's intellect is shown continuously as she Tweets her various "analysis" of the days current events.....mostly self-congratulatory or just self-involved.

Except for Spiro Agnew, I can think of no modern Vice-President less qualified from a mere personality stand-point that Palin.....and outside of her Cultists, I know that lots of Republicans put down atleast part of McCain's loss to the idea of her being a 72 year-old heartbeat away from the nuclear codes.