Mastodon Feed
1. purpose: you're also maintaining an xyz implementation, so, same purpose.
2. nature of the work: the source was unpublished so that's the least-favorable interpretation of this factor.
3. substantiality: hard to say! since it's all chopped up and remixed it's not clear how much input made it to output, so let's give you the benefit of the doubt and just say no harm no foul (a thing that federal judges are famous for doing)
4. effect on market: total obliteration of their xyz product