I use forums and always read and grade every student post, so I think that I understand your question.
Here are two ideas for you.
1) Don't grade forums. If your teachers are not interested in reading quality student's posts, why fake the grading of these?
2) In the grade book, you could go to the forum item and grade these all at the same time, in single item grading mode. Just enter any score that you would like to give the students.
3) Explore creating a feature request in the Tracker system that will automatically give a student a point whenever they make a post, even if there post is something like: "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. "
Since your teachers are not interested in reading what students write, the above "Lorem..." post is as good as any. Right?