I am very experienced in this area since I was a DPE for 21 years. Trust me, a CFI ride of any type does not reset the Flight Review clock, unless the DPE goes out of his way to write the words "all pilot operations checked," which is not the same as the DPE or OPS inspector endorsing, "Flight Instructor airplane single engine practical test passed" as they usually do. You see, it's important to understand that a CFI checkride is not a pilot test, it's an instructor test, and as I've mentioned, the applicant doesn't even need to have a valid medical certificate to take any CFI practical test.
The FAR says that a pilot proficiency check resets the Flight Review clock, a CFI ride is not a pilot check it's as simple as that, or so says the FAA.
In your capacity as a DPE, have you ever administered a CFI ride of any kind to an applicant who didn't hold a pilot certificate with ratings appropriate to the category, class and type of aircraft used for the ride?
If I were a student selecting an instructor, I would want him or her to be a certificated pilot.