Why did scholars say that the Masaa (Sa'ee path) is not part of the Sacred Mosque (Masjid al-Haram), even though it is included within its walls after the Saudi expansion, and considering the rule "that which is close to a thing takes its ruling"?

The Mas'a (Safa and Marwah) is not part of the Masjid (mosque). A menstruating woman is prohibited from entering the Masjid, but she is commanded to perform all the rituals of Hajj and Umrah except for the circumambulation (Tawaf). Sa'i (the ritual walk between Safa and Marwah) is one of these rituals, which indicates that the Mas'a is not part of the Masjid. None of the scholars today say that a menstruating woman is forbidden from performing Sa'i. Sheikh Ibn Uthaymeen and others explicitly stated that the Mas'a is not part of the Sacred Mosque (Masjid al-Haram), and he supported this by pointing out the presence of a separating wall, explaining that if it were included in the Masjid, it would prevent menstruating women from performing Sa'i.