Now, the American Heritage primary definition of "disingenuous" is "Not straightforward or candid; insincere or calculating".
So, he's saying that Mrs. Clinton is not straightforward or candid; that she is insincere or calculating, and that she is a great public servant whom he'd support in running for President.
"I like MY liar" is an awful thing to think, that honesty is a lower priority than ideology. Before everybody screams "Bush lies", actually read what I'm writing here.
Honesty SHOULD be a highly valued thing in a republic's officers. Probably the MOST highly valued. In our polity it's become essentially irrelevant.