They are no longer going to worship him. Siva is an important god of the Hindu pantheon; his worship was strong in the Gujarat region. So it is likely that some Yadavas were reluctant to completely give up the worship of Siva. In another variation, something else. But all these legends carry the same framework. There is something to be gained for which Skanda leaves home and goes out. The most important Gayatri mantra (hymn) of the Hindus belongs to her, it is in her name. She is considered to be the second wife of Brahma, second to Saraswati in importance. And Gayatri being considered as the mother of Vedas, the Vedic gods have been represented as her sons in the Jewish legends. Whoever wins the contest gets both their hands in marriage. And together with her, he fathered the people of this world and created all living beings. And the same is the case with Abraham and Sarai of the Abrahamic world. That was it, he won the contest!
Even they need to be rejected and discarded. Obviously, they would have taken a decision to discard all Vedic gods as well? The only reason why their scriptures talk about Egypt is because their scriptures were intentionally modified by their prophets, under instructions from Moses. This was done to save their faith. Some historians who identified Jews with Yadavas suggested that Yadavas migrated out from India after being displaced by a gigantic flood that destroyed their city of Dwarka. Rebeccah, the wife of Issac, is none other than Ambica, the wife of Siva of the Hindus. Rebeccah of Jews is portrayed as a pleasing and benign woman. And just like in Jewish legend, the Ambika of Hindus is actually a benign and pleasing goddess. The resemblance between the characters is quite striking. In Hindu legends, Swami is a warrior god; he is fit and agile and served as the commander general of the armies of gods. This fits in with the description of Esau, who is said to be an agile and able hunter.
So they needed to be suitably modified so as to fit them and show them as legends about mortals. Some modifications were done here and there to fit the legend of godly figures into the legends of mortals. For example, to justify the attainment of title by Jacob, they have shown Esau as a bad figure; otherwise it would be difficult to justify the guile with which Jacob had acted. So, for example, Tirupati Balaji is called Venkateswara swami. After pointing out all of this, the scholar claimed that this is indicative of the fact that Venkateswara Swamy and Skanda are one and the same; and likewise all forms of worship are different manifestations of the same god, he argued. In south India, Ganesh is considered elder to Swami. It might not be that they wanted to worship Siva alone, but they probably wanted to continue worshipping the Hindu religious trinity of Brahma/Vishnu/Siva and the Vedic Gods; they probably did not want to completely discard the worship of everyone, especially Siva.