Has it? it looks like someone posted the link, and a bunch of random people with no real information (who dont work at google) said "I dont believe it.."

They just pointed out a bunch of SEO problems with the site, that doesn't proof or disprove that they have been censored. Especially if their ranking only dropped on specific terms and it dropped suddenly.

Of course, support.google.com opinion on this matter is entirely unbiased :P

Well, considering it's a support forum and none of the people who have answered are affiliated with Google, yeah, it's unbiased.

I don't have any particular say on this issue in particular, but what about the fact that Google can silently remove replies without telling you (which gives the image of non-bias) and further that people may be biased in favour of Google without actually being affiliated with Google?

If it's merely an SEO problem as that page suggests, why does WSWS rank so highly for "socialist news"?

A lot of sites have SEO issues, but this is not what caused the drop. It has effected a large number of left-wing sites (http://www.wsws.org/en/articles/2017/08/02/pers-a02.html and http://www.wsws.org/en/articles/2017/08/08/goog-a08.html). It also happened directly after Google's new search policy was implemented.