I read somewhere in the report either he or the company didn't use them?
Not correct. The ATSB was unable to recover any checklists due to fire. They are unable to say one way or the other.
The PIC was cleared as competent to fly by a CASA FOI just months before (how many of us can say that?). He had over 2400 hours on type (how many of us can say that?).
Primarily the speculation about checklists arises because an unrelated CASA audit of his AOC showed that the operations manual did not have a CASA approved checklist on the AOC holders format / logo. At the time of the accident he had submitted one which was subsequently approved. Not having a CASA endorsed checklist (as opposed from a Beech one or one from his previous AOC is completely different thing than not using one.
But, still I ask, why wouldn't the aeroplane fly with full LH rudder trim? The ATSB flight sim excercised indicates that it should have.