He moved on from Muzdalifah to Makkah and did sa‘i, but he delayed tawaaf al-ifaadah so that he could combine it with tawaaf al-wadaa‘

There is nothing wrong with that. If a man enters ihram for ifraad (Hajj on its own) or qiraan (‘umrah followed by Hajj, without exiting ihram in between), and he goes out to ‘Arafah and stays there, then goes to Muzdalifah, then comes to Mina, and goes to Makkah and does the sa‘i of Hajj, and delays tawaaf until he is about to leave, there is nothing wrong with that. But this man exited ihram before stoning the Jamrah. If he did that out of ignorance, then he does not have to do anything further. End quote.