A CFI is not a passenger but is a person
On 11/21/2024 § 61.57 of the CFR was amended to change the word passenger to person. The CFI is not a passenger but is a person. While this change may seem minor it does mean that when an instructor is conducting training in an aircraft, either the instructor or the pilot must now be current in that category and class of aircraft.
The definition of passenger was also added. Neither the learner nor the CFI are considered passengers when instruction is being given.