وَإِنْ لَمْ يَدْخُلِ الْقَارِنُ مَكَّةَ وَتَوَجَّهَ إِلَى عَرَفَاتٍ فَقَدْ صَارَ رَافِضًا لِعُمْرَتِهِ بِالْوُقُوفِ
Translation: If the qarin does not enter Makkah but proceeds to Arafat and stands there, that standing constitutes relinquishment of his Umrah.
The decisive qualification is bi-l-wuquf: it is the standing at Arafat, not merely the intention to travel there, that creates this result in the juristic explanation. This case differs from simple lapse of arrival tawaf because the qarin undertook the additional Umrah rites.