He specifically said this is his final offer and he does not want to do back and forth to negotiate the deal. Then why would he do it now? It would look like he

He specifically said this is his final offer and he does not want to do back and forth to negotiate the deal. Then why would he do it now? It would look like he is not keeping his word/promise by not respecting his "final offer". He should just admit that he paid too much for the deal and just pay up and move on.