فَإِنْ فَاتَهُ الصَّوْمُ حَتَّى جَاءَ يَوْمُ النَّحْرِ لَمْ يُجْزِهِ إِلَّا الدَّمُ
Translation: If the fasting opportunity passes until the Day of Sacrifice arrives, nothing except the offering suffices for him.
Fatahu al-sawm means that the specified opportunity to complete the initial fasts was missed. After that deadline, the passage does not treat three later fasts as an ordinary substitute for the offering. Practical hardship in such a situation requires individual juristic guidance.