I think you missed the point of my question. Why does wanting something at time index A, before that something has become technically feasible, make you a bad person, but not at time index B, when that something exists, works and has become socially accepted?

In other words, presumably people in the 24th Century could have the means for reviving cryonauts from the 21st Century, and they could have started to make progress on their own radical life extension as well. Would they go around calling each other narcissists for taking advantage of what they consider the current standard of health care? If not, would they say that about visionary people in biostasis from earlier centuries who expressed the wish to benefit from what the 24th Century people know how to do? Or if some of them survived to the 27th Century and had they friends and relatives in biostasis who wanted revival using the more advanced health care in the latter century, would they say something like, "We're morally okay with our life extension, but those people we knew a few centuries back in biostasis are selfish for wanting what we have. Screw them."

In other words, why does wanting something at the "wrong" time reflect badly on your character?