Which is absolutely correct. If you provide the platform for brazen lies, then you should wear the consequences of said lies.
The exception to this seems to be platforms with user-generated content - YouTube, Twitter, Facebook - as it's incredibly difficult to police. Which is why people can get away with saying practically anything on there. I honestly don't know what you do about these, obviously there are some attempts to counter this (YouTube puts info boxes under some videos, Twitter has community notes), but I'm not sure how effective they are.