I do not believe that they are doing a proper clean room implementation, but I do think it’s possible to do with an LLM.

Let’s say for the sake of argument that the model used on the clean room side is a fully self-hosted version of Nemotron. One of the characteristics of Nemotron is that it’s not just an open weight model, but from my understanding the training set is open, too. So, at least in theory, Nemotron can be proven to be free of any of Adobe’s intellectual property.

Because they’re a popular distro from a comparatively small company, so people who want to attack things rather than build things see them as an easy target?

It’s designed to take advantage of the way eMMC flash works, so it’s very popular on Android phones.