That situation will never happen. There is not a person stupid enough on the planet to think that they can press this situation and get away with anything other than jail time.

Even if you were the most skilled forger on the planet and can produce an exact replica of a bank printed receipt, that still isn't going to display a deposit in the sellers account.

The seller will not authorize a release without seeing cash in their account. They achieve this by looking at their online bank account.

If the funds are not there, the seller isn't going to authorize the release.

The forger, is NOT going to "stand firm to his version". He will know at this point that he has no move but to abandon the scam.

On the flip side, the seller would never be able to get away with anything either because before any buyer is directed to fund the seller's account, the seller has to place the bitcoin in escrow with Bitcoin-Brokers.

The seller knows if there has been a deposit made. If the seller denied the deposit was real, the buyer can return to the bank, and obtain proof from the bank that the deposit was made (because afterall, the buyer would have their receipt as his/her proof). That proof would be supplied to Bitcoin-Brokers, and now the responsibility will be on the seller to prove the bank is in the wrong.

If the seller cannot provide proof that the bank and the buyer are wrong, then Bitcoin-Brokers sides with the buyer and the bank and releases the bitcoin to the buyer.