(1) She is qualified to be a professor at Harvard even if you exclude her work in public service.

(2) Her salary is in line with others in her position and is given in exchange for doing actual work.

(3) Harvard is not in a position to directly profit from potentially privileged information leaking out in her lectures to students

(4) Harvard is not in a position to directly benefit from Yellen influencing current government regulators/policy makers

(5) Harvard is not in a position to directly benefit from Yellen taking a subsequent regulatory/policy position in government