First, allow me to quote from the opening sentence of WP:V: "The threshold for inclusion in Wikipedia is verifiability, not truth — that is, whether readers are able to check that material added to Wikipedia has already been published by a reliable source, not whether we think it is true."  (Emphasis mine)  By making such a judgment and using it as criteria to affect the content of the article, you are committing WP:OR.
Second, I seriously doubt that LS considers this to be literally true, as you are trying to imply.  This is evidenced by his qualification of the statement with a "may be".  This is merely a succinct way of making the point that WMC gains a great deal of influence through his activities here at Wikipedia.  That is the main point and thrust of the article, and on that point yes, I truly believe that it is true.  A great many lay people actually do rely on Wikipedia for at least gaining a basic understanding of the topics that they read here.  GW should be no exception in that respect.  And to the extent that Wikiepdia influences these people's opinions and the way in which they vote in the political sphere, which again is what LS is discussing (as opposed to the science), then yes WMCs contributions for his side of the debate as well as his maligning of his opponents in their BLPs (as LS alleges) clearly could have a significant impact.  Your mileage may vary on the assumed impact of Wikipedia in this context.