Without talking about the anime, there's no reason to have Tenshinhan approaching Kuririn's level with how little we're given of his training, and the plot relevance of Kuririn on Namek is the perfect place to pinpoint where Kuririn gained so much of a lead that he could remain the strongest Earthling until the end of the Boo Arc. Piccolo can't be used as a benchmark for Tenshinhan when Piccolo was shown doing his own thing in most of the glimpses of their training we see. Kuririn wins with ease.