Appealing to "common decency" is just the same as "being owed". I think you're mincing words to avoid sounding entitled, and I don't think anyone is even entitled to two lines in a README, much less at the top.
I agree that it might help avoid conflict/confusion. I do not, however, agree if you say that they "owe" this to anyone. Their (free software developers') work is already a gift to the world. Take it or leave it. No one is compelled to like it or to take it and use it - doubly so for mission critical stuff.
