I doubt there is much dishonor about being shot down by "the best star pilot in the galaxy".
Biggs and Wedge were both basically an extra set of rear shields for Luke in that situation. Wedge says as much in the Rogue Squadron novels.
Why Luke was flying point is probably a better question.
Red Leader ordered it: "Luke, take Red Two and Three. Hold up here and wait for my signal to start your run."
Why would he do that? It was supposed to be a computer-controlled attack that the least experienced pilot could handle just as well as the most experienced. Ergo, the best chance of overall success was to put the most experienced pilots on cover. You don't want green cover that the enemy fighters can quickly blast through to get to the leader.
Not disagreeing with your argument but it's Red Leader himself that takes the failed shot.
Story reasons notwithstanding it's possible his simulator run plus any memories Red Leader had of Anakin Skywalker (deleted scene) made him believe Luke had 'the right stuff'.