is there anything wrong with the social sciences?
Obviously not.
The point of noting her mathmatical background is that she is trained in STRICT REASONING: mathmatical theories and proofs have absolutely no place for biased preferances, agendas, and twisting of existing rules. Social sciences are fine, but are not subject to the same inherent rigor; one can choose a social agenda and manipulate studies & theories to fit (may be proven wrong eventually, but agendas can prove quite durable). In math, one might say 2+2=5 or pi=4, but is plainly wrong and dropped by the wayside. A mathematician is used to creating and accepting proven conclusions which are contrary to what one "wants" to see; in a judge, this amounts to "strict constitutionalist".