This shows that scientists are often way off base from what they thought they knew, so they are probably wrong on the whole dating thing too.
No, that's silly. It is scientists who found these teeth. Scientists use the available information and form hypotheses out of them. Their hypotheses can certainly be wrong, Dead wrong. But that does not discredit the scientific enterprise or those hypotheses which are confirmed as correct!
This "out of africa" business was based on very little information (all that they had). Now there is more information. So the narrative must be altered to accept the new information and incorporate it. To say that because of this, scientists can't be trusted to say anything correctly, would be a serious logical error.
(btw, unlike your evangelical 'friends' at that site, scientists do not reject new information, they have no choice but to consider it all, and changing this theory reflects that).
I must say, these Evangelical Christians are a bit theologically challenged, but they know their science!
They know the "science" (pseudoscience) that they make up, but they do little else except distort actual science for propaganda purposes because the facts uncovered make them uncomfortable and the conclusions drawn from the facts make them uncomfortable.