As much as I, as a general principle, loathe the tech giants dictating what is and isn't true for the world, in this case I feel some sympathy for companies temporarily banning potentially dangerous advice from their platforms.
Yes, it isn't absolutely clear what is "good advice". Yes, it might misfire and prevent useful content from being disseminated. Yes, the WHO is far from perfect. And yet, if I were the owner of YouTube, I would have to reduce the liability of having physical harm, or even human deaths, being attributed to content served by my product — regardless of how tenuous the connection between content and action would be, and how many disclaimers and waivers surround such content.
Collectively, it's a disgrace if all digital media adopt this strategy, because we would be closing the most effective channels by which independent researchers, whistle-blowers, cutting-edge laboratories, etc can communicate with the masses. At the individual company level, limiting potential damage is the rational thing to do. There is no easy answer, I suspect.