If you didn't learn about being a critical thinker in college (or high school, if you're a high school student), I'll tell you about critical thinking.
Critical thinkers look at the biases and backgrounds of the source for a statement. They also look for distinctions between contexts that seem similar but aren't.
It shouldn't surprise anyone that a former attorney general (a political appointee, by the way) appointed by a conservative president would have the view he does on Clinton. It's called bias.
Critical thinkers also consider the context of situations. A retired doctor is still credible on (most) medical issues because medicine, as a general rule, is falsifiable, meaning that statements made about medical matters can be verified as true or false. The statement "this tumor is cancerous" can be proven true or false, since the existence of cancer is an observable phenomenon independent of the observer. It makes no difference who observes it; cancer is cancer in Russia, Indiana, or anywhere else.
Political statements and legal interpretations of statutes are not falsifiable; they can't be proven true or false because their subjects are socially constructed, and changeable. They are opinions, with no truth value. "Jose is guilty of murder" is not falsifiable, because it's truth is contingent upon the definition of murder. It could be true today, then the law changes, and not true tomorrow. This is different than cancer, or there s a distinction between the two. Do you see the difference?
So you see, what you have is a statement of an opinion made by a person with an ideological bias against Clinton, with nothing to lose by making his statement because he is not in a position where he can be held accountable for his statement.
You seem to attach a great deal of importance to his former job as attorney general. While impressive, he was still a political appointee, and one doesn't become attorney general by being fair, balanced, and even-handed, but by being loyal, partisan, and political.
Good luck with whatever you do!