What is confusing is when people describe a scenario in which it is central that an AI has human suffering as a positive terminal value, and they use "unfriendly" alone as a label to discuss it. The vast majority of possible minds are the ones most overlooked: the indifferent ones. If something applies to malicious minds but not indifferent or benevolent ones, one can do better than describing the malicious minds as "either indifferent or malicious", i.e. "unfriendly".

I would use malicious in that context. A specific kind of uFAI requires a more specific word if you expect people to distinguish it from all other uFAIs.