The message from the mod already settles the issue. Mods are encouraged to use their interpretation of the rules as much as possible and to improvise when there are no clear rules. That is what the mod did here by asking you to handle the posts yourself, rather than deleting them and you getting the automated notification.

If you are asking if it is ethical to delete your own posts that have lost their context, it is to me.

You are also not at any risk of plagiarism, you were not claiming the text.

- Jay -