I don't think there is with just the standard Moodle tools.
However, it would not be very hard to write a plugin to automate this.
In fact, it occurs to me that you might be able to use the OU's workflow block to automate this: https://github.com/moodleou/moodle-block_workflow. However, given the current state of the publicly available documentation for this, it is a significant intellectual challenge to work out how. Sadly, I don't have time to write any more documentation now.
We haven't quite automated it, but I have heard of others using a script. What we have done in 1.9 is create an archive category and altered teacher permissions within that category to essentially replicate non editing teacher And tweak a category theme to a different header colour. We then drop courses into this category or a sub category when we want them to become read only. Assume similar settings will be possible in 2.3+.
