It is indeed biblical. You are thinking of the Gospel of Matthew 8:22. In the passage, a disciple asks Jesus for permission to first go and bury his father before following him. Jesus replies: "Follow me, and let the dead bury their dead." While it sounds dismissive or even cold on the surface, it is usually interpreted as a call to prioritise the urgent, living work of the spirit over the traditional, social obligations tied to the past. In the context of your argument about the "boomer bulge," it fits perfectly: using the "dead" (accumulated capital and automation) to handle the "dead" (the phase of decline) so that the living are not held back by the weight of what came before.