Why do Catholics seem to by default consider that anything a non-Catholic says is a lie?
Probably because you people tell so many lies about us (we worship idols, put Mary above Jesus in importance, Constantine was the first Pontiff, etc, etc, etc...) - such statements after repeatedy being corrected can not be dismissed as ignorance but as willful lies. You also seem to have more than a few people in your peer group who seem to me to be flat out crazy.
And note - I don't need to ping a thousand people when I respond to others here. That, IMO, is a sign of a need for attention or an ego problem.
Precedent.