I would argue that by invoking the concept of immortality, you have therefore invoked the “unimaginable timeframe” of infinity to the conversation from the outset.
so it’s not like it was ever not part of the conversation
The better word to avoid confusion here is amortal, meaning it would not die of old age. True immortality is much harder, as accidents would still pose a risk in the long term. Like the janitor pulling the plug on the livable space you set up for the jellyfish, without warning.
so it’s not like it was ever not part of the conversation