This seems like the right first step. Your friend seems to be in a good position to take legal action, but getting tied up in litigation isn't the most pleasant experience.
There's also the court of public opinion. If the infringing party does not want their reputation injured, putting the issue in the spotlight could be an effective move.
For further actions, you may consider blocking this person and/or reporting abuse
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This seems like the right first step. Your friend seems to be in a good position to take legal action, but getting tied up in litigation isn't the most pleasant experience.
There's also the court of public opinion. If the infringing party does not want their reputation injured, putting the issue in the spotlight could be an effective move.