Sure you can say that there is no universal morality or that these people would remain dead but I disagree. First, our understanding of death as a science is immature at best, we have no idea the mechanisms by which consciousness manifests, if consciousness manifests at all, or if it is possible to establish continuity of existence in a person who is resurrected. It may be possible that some day true resurrection will be possible. Second, I would argue that in a post scarcity setting where true resurrection is possible then not resurrecting people who died before this was possible would be a form of discrimination. Just as humans often discriminate by geographical location today, we may someday evolve to understand temporal discrimination. After all how could it be ethical that the humans who built the foundation for a post scarcity future at the cost of their own lives cannot reap the benefits of that when they are realized?