Because it's a bullish*t post.
And it's been posted on this forum over and over again. And it has been previously removed by the moderator.
It's an unnamed source on the internet.
It's meant to push the Plaquenil Bad meme. A real doctor would not do that anonymously on the internet. It would be in really bad form.
It is likely being pushed by the same people who pushed the fishtanks cleaner story.