SMH...he didn't finish the film. So finishing the film by any means necessary even by using a stand in is not "honoring his memory." Call it what it is...making that money the fu*k back. Co-opting that dude's legacy like acting in those F&F movies was the only thing he was good for.
I know it sounds cliched, but in Paul's case I honestly think this is what he would have wanted. Nobody sinks 14 years of their lives into a franchise that they didn't care about. I think this is the best thing they could have done, what better honor to you & your family than to have your brother finish the movie that you worked so hard for? F&F was Paul & Vin's vision, so for them not to finish it or to write him off when more than half of the movie was done would have been dumb.