Can't say I've ever connected at KLIA2 (though AK/D7 do offer protected connections there) but you're assuming Air Asia (AK, D7, QZ) will allow you to check in and print the BP for the return flight so you can get through transit security (if it does exist) and to the return flight gate. I do know it's definitely possible at KUL T1 where you can walk up to the connecting (or in tour case, return) gate w/o a boarding pass..