Any pilot hired of whatever background, will be hired on EBA 4 so now that they have the required Ozzie applicants, and believe me they do, as long as those applicants accept offers of employment, and believe me they will given the plummeting US$, there is no advantage in hiring via 457 visa.
Now if they were offering employment to 457 applicants on lesser T&Cs than EBA 4 you'd have an argument...but they are not.
Storm in a teacup.