None of this is to say that he ought to be confirmed. There very well may be a benefit in finally taking even some kind of a symbolic stand against these radical policies. But if these Senators announcing their opposition to his confirmation were authentic in the convictions they are espousing, they would have been doing -- and will continue to do -- a lot more than simply opposing this single nomination.
It seems that the senators want Mukasey to declare numerous acts of the Bush administration to be violations of law, constitution, and treaty, without taking the next logical step... which is calling for the investigation, prosecution, and imprisonment of those who authorized and committed those illegal violations.