Yes, they do. Censorship of official links is against explicit Wikipedia policy[1], but it doesn't matter because every policy can be overridden by consensus. In practice this means that a handful of professional activists can (and do) censor it as they see fit, since they can determine for themselves whether such a "consensus" exists.
[1] https://en.wikipedia.org/wiki/Wikipedia:External_links#Offic...
I am making a research project on grammatical gender in French, that I host on Wikiversity (there is a dedicated research space there). Lately I get an increasingly large number of rejection of saving my contributions, because some sites are considered "unreliable sources". But in my project, I am looking to document what people use in practice in their written exchanges. That they express lies or try to spread disinformation is irrelevant from the linguistic perspective I’m conducting this project. But due to this software enforced policy, I get prevented from documenting my sources from time to time.
But GP is not documenting the 'true' speech patterns of the people spreading the disinformation, but rather the speech patterns they use when they are spreading disinformation (which, as you pointed out, might be different from their normal speech pattern). So the sources are still good enough for that.