This is a pretty bold distortion of the truth.
They can’t say with statistical confidence what CTE does, but that doesn’t mean there isn’t a link between football, CTE, and the issues it causes. There’s plenty of anecdotal evidence surrounding pain, memory loss, personality changes, etc.
The reasons there’s no definitive link between football and CTE are because of the careful nature of scientific research and the fact that CTE can only be examined in brains after the patient is dead. CTE research is relatively new, and there hasn’t been enough time / sample for rigorous analysis to be definitive.
Also, yes, scientists who study CTE have been careful to point out that there’s no definitive link between CTE and football. But there is plenty of evidence that suggests repeated blows to the head is a major factor for CTE. The question is why some players get it and some don’t.