Part of the human expression of disgust includes thought terminating cliches. Imagine how the average person would talk about a race of bug-like aliens, no matter how advanced they were. It would be a dismissive kind of 'ew, gross'. The humor is in seeing other beings reacting that way to us. I don't think it's supposed to imply the aliens are some kind of flawless geniuses revealing the true nature of human beings.

Sentient plants that move quickly would be another case of us humans going "WTF?!?!"