They don't claim to be. All they're doing is applying existing scientific consensus to new, unverified claims. If after going through legitimate peer review, this treatment Maduro is touting proves to be effective, you can be sure it will be allowed into the discussion as well.

Social media companies take on immense legal liability when they allow high-profile figures to promote unproven medical treatments. The current approach obviously loses a lot of nuance, but the alternative is opening themselves up to litigation when, for example, users ingest fish tank cleaner after hearing from the President that there's a miracle drug which goes by the same name [1].

[1] https://www.bbc.com/news/52012242