I think you have it backwards. Chris Told, Alicorn punished him for it, and the community retaliated. This is a great victory for Tell culture and radical honesty, as long as you don't believe Alicorn embodies them.

A key difference is that the community is incrementalist and consequentialist, while Alicorn is absolutist and deontologist. A lot of the comments don't believe that Alicorn accurately identifies liars. Expelling him is a step backwards from her claimed goal of honest associates. And, indeed, she did specify it was instrumental to this goal and not just a rule she follows without regards to consequences. But it's probably also that. The community's failure to grasp the deontological aspects may make its reaction unfair; but I cannot judge for the same reason. The basic reaction is that she is a very strong instance of Guess culture, where her associates have to guess how much to lie to her and are strongly discouraged from talking about it.