I have a PhD student who has asked for advice on how to go about protecting the identity of interviewees (coded) who have made comments to the researcher that clearly correspond to their published comments.
My PhD student is concerned that the close correspondence between the material he had gathered during interviews and the published work by the interviewees will help reveal the identity of his interviewees.
A large number of his interviewees also appear in his bibliography and references.
Does your PhD student need the interviews when they are in line with what the interviewees’ published comments? If yes and confidentiality is threatened by quoting from the interviews, your student might use this as background information that one can trust the published commitments and try to argue for credibility without referring to the interviews. Not optimal, of course, but confidentiality goes first when it was promised.