You're right that this is a gray area. And there's nothing wrong with your choice.TimTaylor wrote: I felt including the endorsement as a flight review was somewhat of a grey area and chose not to do it that way.
The alternative interpretation is that when a CFI has given you instruction and signed you off as trained, you are then at least authorized to go on to flying a proficiency check with another CFI, during which you are PIC. If authorized to be PIC (albeit only with a CFI as your first passenger), you are sufficiently rated in the aircraft to have the proficiency check count as a BFR (if the instructor chooses to so endorse you). The proficiency check will typically include at least an hour of ground (the oral) which includes a review of the relevant FARs, as well as an hour of flight. So, it's up to that instructor, of course, but can constitute a flight review.
If you happen to have a current medical, and choose to take a PP level checkride with a DPE (which Jack Brown's allows), then the BFR is automatically satisfied. But since the training and "checkride" are the same in either case, they seem comfortable with signing off the BFR for a SP proficiency check as well. Here is a case where it's probably best not to ask FAA Legal for a Letter of interpretation (unless you're prepared to receive an answer you don't like).