The Pope wandered off into heresy; Church teachings did not and the Church took it seriously enough that it took the steps as drastically as it did to make sure that any error lurking in the wings or under the carpet were eradicated. You must admit that the reaction was pretty drastic.
Some say a lot of things; look at the current crop of Presidential candidates for instance. It doesn’t make them either true or untrue.
Was he a true Pope? Was the line broken?