Jfresh probably is legit in this case where he sources from the NHL's official numbers. That can be double checked and verified.
In general though, I understand the suspiciousness of him. All he's doing is putting numbers into his equation and that source equation or source numbers can't be verified. So that leaves the possibility that he can editorialize the results as he see's fit. A couple of War Points off for this or that player, who's to say. No one can know.
I also find the whole practice of Charging for STATS ridiculous. Now if he was personally out there counting Corsi events to create WAR then, sure charge for it. But he's taking public numbers, putting them into a Personally determined equation and weighting based on years of OTHER peoples work to build the WAR model in the first place, then charging for that? Seems scummy to me. In the past this would be the work of a hobbyist/enthusiast and provided to the NHL community for free.