The only naive people here are the people defending Saint Bernie and actually agreeing with him that Hillary Clinton is unqualified to be President. I for one think both are qualified, as is our President, and that Sanders' comments are the result of a desperate campaign that has no hope of winning the nomination.
At the end of the day, Sanders deliberately misquoted her, and used that as a basis for a personal attack against her. I would expect a reinvigorated Clinton campaign out of this (from what I have seen/heard, fundraising has spiked) and that Sanders is going to turn off a lot of people with these grumpy gutter attacks that really are above him.
I think they're both qualified as well. But aside from loading the "qualified" language into it, the attack was on policy and judgment, not personal, right? Unless I'm misunderstanding where people are placing the line between the two.