It's unethical if there are any safer, viable alternatives. In systems programming, there is little reason not to use Ada for instance (hopefully Rust soon).
Finally, classifying the creation of something as unethical doesn't necessarily entail its use is unethical. An unethically developed cure for cancer would certainly be widely prescribed and used, despite the long history of medical ethics.
Finally, classifying the creation of something as unethical doesn't necessarily entail its use is unethical. An unethically developed cure for cancer would certainly be widely prescribed and used, despite the long history of medical ethics.