I agree with you on the first one, but that second one he had to bury that. Lukaku had been made fun of for that kind of miss.Thuram missed chances are not as easy as it looks. On the first one he was hardly pressed by Fio defender. On his second miss he was not marked, but the pass was too strong and the player receving the ball need a bit of luck to hit it at the right angle.
All in all I don't consider his first miss a big one, but he could do better on the second one.