This isn't really much of an argument. The defining characteristic of a non-rotting codebase is one in which you can update your dependencies and language version every six months or on CVEs with only minor changes.

If you think rotting sounds too negative how about "maintenance unfriendly."

Your argument was about unmodified code, not mine.

If you only want minor changes, don’t install new major versions.

How does that work in an ecosystem which is constantly releasing new major versions and not backporting security fixes to old majors?