Why would 7000 employees have such hatred for a sister company?
I don't think they hate the people in the company (excluding management). They probably hate the principle of the company (to undermine mainline jobs, pay pretty poor wages and undermine the industry in general..... just joking on the last point
).
Or maybe they just hate the jetstar advertising campaign - 'worlds best low cost airline' which seemed to be a little far fetched at best. (but hey maybe it was true.....