Oh, really? What is he/she then?
AFAIK, he is either an instructor, in which case he is PIC, or he is a passenger. What other alternative is there?
He/She is a passenger who goes by the title of Instructor as far as he is concerned.
28 day rule is usually a club thing or insurance, it is NOT a requirement of someones licence. As previously stated and we have had this 'discussion' several times on here, unless you agree beforehand its an instructional flight then you are P1 the 'Instructor' can enjoy the view.
I did a 'check flight' yesterday in our group aircraft guess what - it was P1 for me. Unless the club states that his to be an FI does the 'safety pilot' or whatever term you wish to use, have to be an FI? Insurance requirement? Certainly not on our aircraft.
Like I said, this one splits the camp.
J.