But your grade on the final (76%) is lower than your other test scores. You didn’t meet the requirements to have any tests dropped. That is a completely fair result, as his policy was stated before the test.
I’ve had professors do this before and there’s absolutely nothing wrong with it. People get the grade they deserved based on whether they had learned the material by the end of the class (which is what really matters). I had one prof double count the final and drop our lowest test score, assuming our final was our highest score. I aced that final (perfect score), so I got an A+ in the class. I took another course with that same professor where she didn’t have that policy, and even if she did, it wouldn’t have helped me. I had a 97% in that class going into the final, but bombed it, so I got a B+ in that class. Does it really bother me? Yes, but only because I blew it. It was no one else’s fault. I was the one who didn’t study hard enough and didn’t know the material for the final.