It's not a TODO yet, it 's a note that says if you think this would be a good idea, do that instead. It's a potential TODO-to-be, waiting for the need.
Is that better? That would mean that they have a method in their API that they don't think anyone should use but haven't deprecated it or documented it that way and have no plans to do anything about it.
strings.Compare is mostly used in trivial demonstration programs, and is there because bytes.Compare is there. It makes https://pkg.go.dev/sort#Find documentation simpler. Deprecating strings.Compare would make sort documentation worse.
Real code tends to not be that trivial, and that's why real code most likely shouldn't be using strings.Compare.
