I also think a lot of people here are overestimating how broad the agreement is on what is ethical and what is not (and thus what would be prevented from happening under such a "Hippocratic Oath").
Examples being: Microsoft/GitHub's work with ICE, Google's China search engine, use of AI in military applications
I personally have a strong opinion on some of those, but I'm not delusional enough to think that there are no competent software engineers that disagree with me.