I agree that a blog post would be more helpful, but the barrier to creating one is higher. This sort of update wouldn't fly there because its an off-the-cuff status report that will be buried in a day or two. The Let's Encrypt blog will be available and readable for all eternity (give or take a few years), so it requires an update that's more in-depth and vetted by all the people involved in solving this issue.

I'd imagine that once they fix this issue the first thing they'll do is to post a post-mortem on their blog.