I don't see what the issue is. You can either delete them while you still have the subscription, or you can make them public and keep them after you switch to the free plan.

The checkbox clearly informs you of this fact. If there wasn't a checkbox like this, people could be confused either way--some will think it that everything is deleted and be surprised when it becomes public, but others would expect everything to stay and be shocked when it is deleted.

Also, if you wanted to stop using the service entirely, you would go to the page for deleting your account entirely, rather than just downgrading to the free plan.