I believe Alec Knight was 7.5" in his prime. I have watched a lot of his scenes and he was longer than most of the guys he appeared with. I cant comment about his dumb measurement, only it is a silly one.
Remember the 6.5 Criss Strokes measurement? On rare occasions dumb measurements are performed in porn that go against the porn-star. Only rarely, but it happens. Not everything in porn is a conspiracy to make the guys look huge. Sometimes they shoot quick scenes and embarrassing things happen.
The same thing happened with John E. Depth, there is a measurement photograph where he is not fully erect, now about 80% of the users on here claim he is 7.5 at the most.