"Subjective" how exactly? There are surely some variations, but if this is about "my wallet has feelings too" morality, that would be all the more reason we'd need an (enforceable) code of ethics.

Subjective in the sense that something you find morally wrong i could find it morally right, or morally neutral. E.g. for the specific issue of this thread, I consider what they did to be morally neither bad or good. The developer has no obligation(moral or legal) to check with me before commiting stuff in the repo he controls. He doesn't owe me anything. In fact I could say that I owe him (morally, by my moral standards, because I 've been using his code). But that's just my view.

Well yes but morals and ethics are almost by definition about valuing the interaction between people. As such, even if you assume that moral is subjective, if you only have your own personal morality, that's rather useless - it only becomes useful if you can agree with some other people about common rules of behavior.

You could say for yourself "I personally don't believe in private property, so I don't see any objection with theft" but my hunch is that this argument wouldn't do much to calm the victim of your theft.

That proposed code of ethics in software seems like an attempt to create exactly such an agreement.