You're saying that there is no conclusive evidence that Tylenol causes autism, therefore, we assume that it does and should not give it to children or pregnant women.
By this logic, I see that there is no evidence that Donald Trump has a tiny dick and hence we should assume that he does.
Lack of conclusive evidence for something does not mean we assume it to be true and behave like it is. Our whole legal system is based on the fact that when accused of something, lack of conclusive evidence does not mean the accused is guilty. Without conclusive evidence, the accused is deemed not guilty.
Similar principle applies in science. since there is no conclusive evidence that a comet is on the way to hitting earth, we do not assume that is happening and freak out.
BTW, when experts say use caution with medication, they mean use the medication for the circumstances and in doses specified by the doctor. The orange lard-o-maga is saying that if the doctor tells you to take Tylenol, don't listen to the doctor. Do whatever the fuck you want.