You won't be withdrawing and $$$ from the RMAH anyway so whats the worry?
Any money that goes into to a Blizz wallet is owned by Blizz and can only be spent on virtual blizz goods and/or game cards for online games. You wont be able to withdraw like an ATM.
When you sell an item on the RMAH, people will have to put money into their Blizz wallet to buy that item...again money that can not be taken out.
I believe you are wrong. You can get the cash, after about 10-12 "fees".