Thank you for the idea. Currently, when a release is cloned all assignees for the features in that release will automatically be assigned to the features in the new release. If you need all of the features to be assigned to a different user we would suggest using bulk edit from the Features -> List view. This will streamline the process as you can reassign all of the features to a single user in one step.
Given the suggestion above and other priorities, we are unlikely to implement this idea at the current time. We hope you can understand.