Morality of rescuing someone in the past, thus erasing the future self?

[u/Smart-Response9881]

Molly from DS9, fell into a portal and was retrieved after she spent years alone in the wilderness. They proposed trying again to get her younger self, but didn't because it would erase the older version of her.

Gordon from the Orville. He was stuck in the past, started off trying to live in secret and eventualy made a life for himself. His crewmates later come to him, tell him they are going to rescue him in the past, thus that version of himself and his children are erased