The analogy Prof. Dubal uses is not apt. They seem to believe that the extension was some kind of public notice board where anybody could post something, but that is not what it is. Since they did not have sufficient context, I would be disinclined to trust their judgment on this issue.
Also, FWIW, this may provide some interesting reading: https://www.hg.org/legal-articles/are-employers-required-to-...