There is a phrase blissful ignorance that has been in use for centuries. Examples can be found following this ngram.
Oxford Dictionaries Online defines it as
Fortunate unawareness of something unpleasant.
As the definition indicates, its application is much broader than erroneous pontification, and the unpleasantness will be felt by the listeners, not the speaker.
Talk at length, especially in an inflated or empty way.
Oxford Dictionaries Online
Again, this is broader, and may include talk that is hollow, but not necessarily erroneous.
Or you might coin your own phrase, such as master of misinformation.