You haven't provided any good reasons to think this... as I've already pointed out, the (longer) ending of Mark is cribbed together from other New Testament texts that are stable in the manuscript tradition and even more explicit about Jesus' divine status. Your hypothesis crumbles on this point even before attempting an integration with the historical situation. Your comments related to this reflect an outdated and improperly-nuanced model of the relationship between Jews, Christians and pagans in the Greco-Roman world. The pertinent point of departure relates to Christianity's position vis-à-vis Judaism --- while it is true that the latter enjoyed a measure of imperial endorsement for their peculiar monotheistic practices, this elicited both admiration and disdain from their pagan contemporaries, at times leading to hostilities and persecution. As Johnson points out, "Jewish separation had legal protection but not universal popular approval" (113). Even that legal protection was tenuous and subject to the whims of local officials and shifts in power, as the attacks on Jews in Alexandria within a decade of Jesus' crucifixion attests (Barclay 48-55). Identification with Jews thus had the potential for both benefits and persecution, which problematizes the scenario you outline...Jews were exempted from sacrifices to the emperor but they had to pay a special tax. Until the destruction of the temple, Christians generally worshipped in Jewish synagogues and were considered a Jewish sect.
As time went on Christians who openly professed the divinity of Christ were expelled from the synagogues. Romans no longer considered them a Jewish sect so failure to sacrifice to the emperor was a capital offense but enforcement depended on the whims of local officials.
There were good reasons not to write down the ending for the Gospel of Mark.
Barclay, John M.G. Jews in the Mediterranean Diaspora: From Alexander to Trajan (323 BCE - 117 CE). Hellenistic Culture and Society 33. University of California Press, 1996.
Johnson, Luke Timothy. Among the Gentiles: Greco-Roman Religion and Christianity. Anchor Yale Bible Reference Library. Yale University Press, 2009.