The Ethics of the Unreliable Framing Device
Launch library · evergreen read

Fiction can use an unreliable narrator deliberately, trusting readers to notice the gap between what is told and what is true, but nonfiction generally cannot borrow this device without misleading an audience who reasonably expects a narrator to be presenting the evidence honestly and directly.
Where a nonfiction piece does use a limited or subjective framing, perhaps following one person's understanding of events as it unfolded at the time, that limitation needs to be made clear to the reader rather than exploited quietly for a purely dramatic effect on the reader.
The difference between honest limitation, clearly signalled, and unreliable framing, quietly withheld for effect, is really a difference in whether the reader has been given what they need to interpret the account correctly and fairly. A brief, honest note about the limits of a particular vantage point costs a writer very little and gives the reader exactly what they need to weigh the account appropriately.