HR Leaving feedback?

[KungFuPandaWorksOut20]

Posting on behalf of a friend.

She left a company almost 3 months ago, due to workplace bullying that management didn't tackle. She received an email last night with a leavers feedback, in the email it asks her to be as open and honest as possible and it will all be confidential.

She's prepared to reveal everything and be as honest as possible, whereas I'm confused as to why 3 months later they will send this. AIBU in thinking there's another motive, and it's being disguised as feedback.

If she was working for my previous employer, it's entirely possible that HR are so f'ing useless that it just took them 3 months to send the survey. Another possibility is that they weren't originally going to ask her for feedback as they knew it would be negative (I never got invited to provide feedback) but now other things have come to light about the bully / bullies / management and they now want her feedback to help build a case.