Yes, that's certainly possible, but it's also out of my control. I have basically three options:

1. Delete account - we know this doesn't delete comments
2. Delete comment - "seems" to delete comments, but we've seen comments get restored - so probably using a "deleted" flag
3. 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.