Your comment existing has a carbon footprint, doesn't mean it should be paired with the dairy industry's

Plus the simple effects of land conversion. Plus the emissions from the feces.

Yeah. But since farm animals are often fed from farmed plants these days, animal-based tends to be worse by quite a solid factor. This article puts butter at 4x worse than margarine, for example: https://www.forkranger.com/blog/is-margarine-a-sustainable-alternative-for-butter/

How plant-based compares to this new process still needs to be seen for sure. If it's just a machine you can plug in at the store and everyone can get their butter like out of an ice cream machine, without transport and cooling chain, then it's likely a lot better.
But at this point, I don't expect the process to be much more efficient than what plants are doing, which means you'd still need a ton of energy and particularly also land area for it.