And what is the injury or harm of that? The developer said they wouldn't action the change and indirectly suggested the user to fork it - "it is open source after all".
>2. The software will have one more competing product (forked from their own work).
This is the very nature of open-source software. Labeling it a "competing product" makes many assumptions that aren't earned. We're talking about a user saying an opt-out feature should be opt-in. If I forked LibreOffice because it contained features I did not like, am I now making a competing product? Am I harming or injuring the repo I forked? Am I fighting the LibreOffice developers?
>Most people willing to put their time and energy into building software for others would consider losing users to be a moderate negative and having their work potentially forked and having to compete with a derivative a strong negative.
The developer didn't seem to consider it a moderate negative.
>“We will fork” is a strong threat. It is basically a statement that “we” will fight the maintainer for the effective future of the project.
You're expanding the scope of what was said. Saying "I will fork your open source software" [to make an opt-out feature, opt-in] is not "fighting" the maintainer for the "future of the project" - it's a core element of open-source software.