An atheist, like anyone, can be considered hypocritical.
Were an atheist to deride and criticise and mock a person of faith who refused to change their faith when they are presented with incontrovertible evidence to the contrary, that self- same atheist would be hypocritical if they in turn would admit of or recognise no phenomenon, evidence or observation that would prompt them to change their opinion and give them cause to believe in a god
This tends to be one of the fundamental differences between those with a religious belief, and those with a lack of belief,ie atheists. The latter can posit a standard of evidence or observation or phenomenon that would persuade them that their lack of belief was false; Those who have a faith in religion either cannot or,more likely, will not.
And regarding your point about atheism not being a belief modeller ,I agree entirely - but several contributors here, and many in the wider world outside of AB, would disagree.
For them, the definition of atheism is a positive choice to disbelieve in gods.Atheists would disagree - A positive choice to disbelieve in gods, to reject the supernatural, should more properly be termed anti- theist :)
Atheism is very simple - a lack of belief in a god or gods.