Let's consider something else that is closer to the nature of the tool at issue. Something simple, like the development of nuclear physics during the first quarter of the twentieth century. (Actually, it is quite simple; but that's just the chemist in me speaking.) The theoretical basis for nuclear physics has a necessary collateral effect that had overwhelming consequences in the last half-century, and may yet make them worse: nuclear weapons. A system of reasoning that adequately explains the nucleus also provides all of the tools necessary to theoretically specify and develop nuclear weapons. The difficulties of actually making nuclear weapons are engineering issues, not scientific ones; that is, they are questions of application, not of methods of reasoning. Just as with the specter of "supporting Roe v. Wade" raised by the Perfesser, reasonable people can differ on whether nuclear weapons have had a positive effect by constraining open warfare in Europe for the longest stretch in centuries or a negative effect with their terror and actual use. The point, though, is that the method of reasoning does not force the actual development of nuclear weapons; it only makes that collateral effect possible. Perhaps unavoidable, given the context of the human desire to enhance might; but one could choose not to go that route. One can make a similar argument from the germ theory of disease to genetically engineered biological weapons.
Of course, some extremely specialized tools really are inherently of a single moral class; the guillotine comes to mind. Then there are unintended consequences, such as the cotton gin (which was intended to end slavery, but actually expanded it). That is not to say that the kind of scenario the Perfesser imagines could not have an unsavory moral implication—just that the particular one specified does not. Creating an "interpretive tool" would have a moral consequence if, and only if, the feared immoral result was not just a collateral effect, but a foreseeable and perhaps even intentional effect of creating that tool. That the tool the Perfesser describes can be used equally well in demonstrating an internally consistent rationale (or, as the case may be, internally consistent error) for a variety of decisions reinforces this conclusion.