You should use "very low quality" for posts that are very low quality. The post you flagged was not very low quality.
If a post is "off topic", you should, according to How should my flagging change when I gain the ability to vote to close?:
- If you're below 3k:
Flag as off topic with the appropriate site selected, or a custom message.
If you're above 3k:
Vote to close as off topic if there is a site you can select (e.g. Web Applications).
Vote to close as off topic and flag, if there's no site you can select (e.g. Wordpress).
And, to emphasize again:
Do not flag for moderator attention when you already have the power to close and migrate questions.
This was made clear in this Meta.SU post.
