Answer is simple, your friend should get the same as every other crew member in the base/ country they are employed in (which they do).
We are talking about a senior vs a junior Australian based crew member, working under the same EBA ( ie work contract)
one gets disadvantaged for no other reason than seniority (a disadvantage that those who were employed long enough ago to be in the top 20% never had to put up with - so even "tradition" or "rights of passage" could not be argued).