well concerning the assignment of rights, I think it means, the client cannot assign the rights to somebody else ( like trying to use them as security with a different margin lender ). I don't think it means Opes can't assign the rights.
Also, if your interpretation is correct, that Opes should not have been able to assign the shares to ANZ, then also, Opes should not have been able to "lend" the stock out for shorting either. Lending stock out is surely an assignment of rights.
