He's pointing out that just because near-infrared light on one end of the spectrum may have some beneficial effects on tissue, that it doesn't necessarily follo

He's pointing out that just because near-infrared light on one end of the spectrum may have some beneficial effects on tissue, that it doesn't necessarily follow that using some light of pretty much the opposite color will reliably allow a dentist to yank out your tooth without pain. Equating the two was the big logical fallacy here.