Totally legal, it is the candidate who can be in trouble, but the tool maker cannot be liable unless the tool's purpose cannot be anything but illegal use.
I'm not sure I see how this could be illegal. It has a perfectly valid use - interviewees who are deaf or hard of hearing.
Maybe I'm naive or don't have a good enough mind for cheating, but I'm not sure I understand how you cheat at an interview with this. Because you can read the interviewer's question? How is that cheating?
Redirect the question to chat gpt, read the response aloud. I think that this was mentioned initially in the post but might be in error. Chat gpt is not necessary, as far as someone else is giving the answers.
Maybe I'm naive or don't have a good enough mind for cheating, but I'm not sure I understand how you cheat at an interview with this. Because you can read the interviewer's question? How is that cheating?