My Sim kept receiving retirement prompts and I kept declining because she was nearly done with career and hobbies. One time I declined too fast and bam she’s retired, unable to contribute and I’m unable to undo a non confirm-button action.
I kept the retired Sim because I figured she could mentor. After a couple days, she had an event pop up for relationship. Today the event icon is back with a mentoring option. All it gives is Good Upbringing boosts, so I don’t know yet that it’ll be worth doing.