Thanks for posting that link. This Mueller quote in the article is unclear: “We’ve got the first flight version of that engine in work”. I assume “in work” means “in production”. Which is great news!
Tom Mueller wins an award from The Space Society. He gives a presentation on the development of the Merlin engine. It starts at 4;00 in the first video: Part 2
Article on Tom: Meet Tom Mueller: From Idaho logger to SpaceX co-founder who makes Elon Musk's rockets fly
Tom retired yesterday (nice Taycan there): https://twitter.com/lrocket/status/1333537793335693312?s=12