In case a user loses its private key, the user won't be able to interact with the issue, repository, and so on. We can think about it, if we want to add the possibility, that in case this happens, we are able to do something about it, like change ownership of the repository or something like this.
Honestly, it would be better if the user uses instead a wallet like Argent or so, where in case of a lost key, the Guardians help out :)