GOATS do not trail their biggest rival 2-5 in slam finals (2-6 if you add a semifinal).
That is a lop-sided tally though having to play the best clay courter of all time on clay for 3 of those 5.
The best player of all time (whoever that is) on either gender would beat their biggest rival on every surface. Graf beats Seles and Navratilova on every surface in the slams and elsewhere. Navratilova destroyed Chris Evert, the greatest female clay courter ever in the 84 French Open final. Evert has beaten Navratilova at every slam, including her beloved Wimbledon (ok semis not final but still).
Laver has bested Rosweall and Gonzales on every slam and on every surface, including a straight sets win in the French Open final over Rosewall. Sampras wasnt owned by any opponent, despite his failure to win the French. He has even beaten most of his eras greatest clay courters at the French head to head though- Muster, Courier, Bruguera. Borg beat McEnroe and Connors on every surface, and beat both at the U.S Open, just never got the 7th win to win the title. Budge beat Perry and Riggs on every surface and won the Calender Slam.
Federer has never beaten Nadal at the French. Nadal has beaten Federer everywhere. In the last year Federer at only 26/27 has lost 3 straight slam finals to his biggest rival on 3 different surfaces, and the one on Nadal's surface was trounced. Sorry that isnt GOAT material.