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?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 postthis Meta.SU post.