i would say that link wins the Marth matchup, not because of SAUS v Moon (trust me, i believed link won before that match), but because he actually forces Marth to approach in a way that most characters cant do. He can also trap Marth in up-airs, which has more range than Marth's down-airs. His grab out ranges any of Marth's ground moves, and while not being able to grab in the air, he can tether to make himself harder to edge guard. A lot of his grab combos work exceptionally well against marth, and he has several tools that work well for edge guarding. I would say that although the punish game does work only slightly better for Marth, Link's neutral game is very much stronger than Marth's, because he has the projectiles to try to force Marth to attack, and he has options to out range Marth.