What if the Ottomans had accepted the Allied terms?

Would the powers have intervened against the Greeks if the Ottomans accepted the settlement and withdrew?

Probably; the Allies wanted a bounded settlement and would have restrained Greek expansion beyond it.

The proposed settlement was not a license for unlimited Greek expansion. An Ottoman acceptance and withdrawal would have removed the immediate opponent the Greeks were fighting. If Greek forces then built up for an offensive into Ottoman territory, the same powers enforcing peace would probably have restrained them. Allied support was therefore a bounded settlement designed to restore balance, rather than an open-ended commitment to Greek conquest.