What an intriguing claim  Nope  we can not ever use opinions as fact in Wikipedias voice  Where a news source specifically attributes opinions to specific persons that attribution is the fact and the opinion remains opinion    Is this quite clear   George Gnarph called Wilbur Wharf a raving lunatic is an opinion  we can not use it to say William Wharf is a raving lunatic or make any such implication that William Wharf is widely viewed as a raving lunatic