. . . present a warning to anyone running as root that attempts to do this?
The last time I was really active in any Unix environment was in the late 1990s, and even by then a great many varieties of Unix would not allow someone running as root to issue this command without questioning it first if they were sitting in the root (/) directory.
This is a curiosity question, as I observed (and luckily had no part in) someone accidentally doing this and wiping out and entire system in a business setting.