Hi again Rachel,
I had a look at the death records for NSW for an Arnold E. Holt but found none at all.
Not knowing where in Australia Arnold was makes it hard to trace him.
Have you tried to finding him on the shipping lists which are posted on this thread?
I think your best chance is to find a record of his death. As this thread has been answered a few times other RootsChatters may not read it thinking that the post is completed.
You could post again on this board asking for a lookup of the death records in other states - and noting that Arnold doesn't appear on the records for NSW.
Regards
Darcy