He stems from an ancient Skakdi fear of Kaita formation.
He’s a Kaita combo of 3 P****a sets, a Kaita is a merging of both mind and body, and Irnakk messes with the mind and can make body horror happen to others, as seen in Hakann and Thok.
It also doesn’t even have to be a physical merging, it could also be their distaste of working together to achieve elemental powers
Why is this censored?
Because Poopya is a bad word, DuneToa 
It’s an interesting theory, and I’d like to think Spiriah’s manipulation of the Skakdi species had something to do with the formation of the legend. Maybe the myth of Irnakk came about due to to the Makuta’s attempts to turn the Skakdi into an Anti-Toa of sorts, complete with Kaita and all - and that being such an unnatural state for them to enter drove them mad and lead to the terrifying tales of what could occur.
Why you censored Piraka, @Psychic?
LANGUAGE, Spiderus! Good grief…
Pretty neat theory. Like Ghid said, it’d make sense if it’s some inherited thing from the experimentation days.