According to description section of STATVFS(3) manual page, the function returns garbage. This statement is very childish and doesn't provide any value to the reader. Furthermore it puts FreeBSD project in rather negative light. If the function is not usable then please state so and suggest an alternative.
It's one sentence; the manual page is otherwise well written and clear to readers. If you have a concrete proposal, please share the patch. I don't think this is problematic or "puts FreeBSD project in rather negative light."