Having a different opinion than someone else and presenting the case is one thing, but my goodness berating other sellers for leaving a non-hysterical truthful comment for a non payer is a bit over the top IMO.

I also leave honest comments for all my buyers, and have done for several years.  I do not expect them to be removed as IMO my comments are within the eBay feedback policy parametres.  eBay has also never advised me that any of my comments have been removed.

I have little doubt that at least some of the comments I have left have, along with other sellers, provided a useful heads up to other sellers when non-paying pests have purchased their items not to drag their feet with opening an unpaid dispute.

Feedback is subjective and is removed regularly, with very few buyers or sellers ever reporting sanction by eBay on the boards due to a comment they left being removed.  That is not to say that does not happen, but who really knows, eBays application of their own policies is random at best.

There are loopholes that allow feedback to be left after a non payment case is closed and a strike has been issued.