Is Sa'i obligatory for the people of Makkah during Hajj? What are the consequences for one of them who performed Hajj Ifraad, and performed Tawaf Al-Ifadah after Rami of Jamrat Al-Aqabah without Sa'i, then performed the greater disengagement (Al-Tahallul Al-Akbar) and touched women? What is the expiation for that? Is the greater disengagement achieved by Tawaf only?

The pilgrim must perform the Sa'y between Safa and Marwa, as it is a pillar of Hajj without which it is incomplete. There is no difference between the people of Mecca and others in this regard. The major 'Tahalul' (permitting of previously forbidden things) is not achieved except by performing the circumambulation (Tawaf (definition)) along with the Sa'y. So, whoever performs Tawaf but not Sa'y has not achieved 'Tahalul', and must refrain from intimacy with women. If one enters into 'Ihram (definition)' for Umrah (definition) after Hajj, while still needing to perform Sa'y (for Hajj), their 'Ihram' for Umrah is invalid, and their Sa'y will be counted for Hajj. The intention for Sa'y is sufficient; it is not a condition to specify it for Hajj.