Yes, that's certainly possible, but it's also out of my control. I have basically three options:
Delete account - we know this doesn't delete comments
Delete comment - "seems" to delete comments, but we've seen comments get restored - so probably using a "deleted" flag
Edit comment with nonsense and when delete - should poison comment if they're just using the deleted flag
That's it. There's no guarantee it works, but it has a much higher chance of working than the other two.
And there's a good chance they delete old backups. Hosting every edit is expensive, so there's a decent chance they clean up old data after some months.