No. “[All] rankings are bad”–which I did not say–does not mean “all rankings are equal.”
The ARWU metrics look like reasonable proxies for research power (*prima facie *), though one could use other metrics or weight each metric differently. Those who dismiss ARWU as irrelevant might still accept that a University’s numbers of Nobel Prize winners and highly-cited researchers reveal something about its “contributions to knowledge.” Indeed: the ranking seems internally consistent, even if consistently wrong. (N.B. I imagine that schools can skew their “research income” or “academic staff” totals with minimal trouble; falsifying Nobel and HiCi counts is harder.)
What does the RUR demonstrate? Perhaps the number of ways in which you can rank Harvard #1, but not much more. Since the ranking agency provides even less data than the ARWU compilers–only each school’s ranking in each category, as if the extent of difference doesn’t matter–the RUR comes off still worse in comparison. The RUR’s convolutedness brings it to incoherence; its opaqueness, to unsalvageability.