There was a period of time between 2001 when QF bought Impulse and when Jetstar was started in 2004, that Impulse operated as QLink. AIPA were slow to understand what was going on and took a while before they come to the realisation that the other Group airlines were here to stay and they needed to reach out to those pilots. From memory that didn't start to happen until around 2008.
Or they were under strict orders not to do anything. Given the number of AIPA Presidents who magically have ended up in QF management my money would not be on they didn't understand what was going on. Blind Freddy could see what was happening but you have to actually want to represent Pilot interests if you want to do something.