I often deliberately publish code with no license. It means any hobbyist can play around with it, but no company with a legal team will touch it. It appears as an oversight rather than a deliberate decision to restrict who can do what. And often that's exactly what I want.
I don't think that's helpful, because that's just not how licenses work. Please at least add that sentence to the repo then. Unless your definition of "hobbyist playing around with it" also includes "oh, I accidentally made something useful which uses your code, but now I have to rewrite it because I can't in turn use a useful license".
To really make a point, one could include an empty file for the license (and code of conduct as well).