Yea, that's confusing, despite not being wrong. It is a juxtaposition of two completely distinct phenomena on one graphic, which is confusing, for sure. But the whole article is about EM waves, not sound waves.
Sigh.
Sigh.
I also shared the same information as your 2nd (aside: sound doesn't require air, as bone conduction headphones or scuba diving demonstrate, does require "not vacuum") and 3rd paragraph, and made the same point as in your close.
So I agree with you, which is why I objected to the graphic.