I don't think that fact that you're only looking at lossless compression is clear enough in the post. People see "JPEG" and "compression" and they assume you're talking about lossy compression. The post doesn't include the word "lossless" to describe what you're doing, people have to figure it out.

Happy to hear you're seeing benefits from mozjpeg, and I look forward to the results of your work optimizing run-time performance. Thanks for giving mozjpeg a shot, publishing your results, and contributing back!