Whether you believe in Catholic doctrine or not, if you understand how it is we see it, you can see why this is appallingly horrid.
Of course. Flushing a Communion wafer down a toilet is clearly an insult to the Christian faith in general.
However, I can see how refusing Communion to a Protestant Christian by Catholics was also insulting, because it happened to me once, and I have never gone back to a Catholic Church since.