There's a very significant chance this infinite isn't even practical which is important to keep in mind. Even if it is though, it really is more about avoiding arbitrary rules. As a competitive community, we strive to play the game as it is, not as we want it to be. If Robin (or any other character) is subject to an infinite or another abusive tactic, that's a real shame, but it's acceptable. This is, incidentally, not "unfair" at all; the concept of fairness is often misunderstood. Every player has an equal and fair chance to pick any characters on the character select screen. The relative imbalances between those characters are not unfair; it's a legitimate part of the game's skill test to pick one whose disadvantages you can mitigate, whose advantages you can emphasize, and whose overall true worth is high enough to allow you to win. In other words, even in the (unlikely) event this infinite just ruins Robin, that's still not unfair because no one is forcing you to pick Robin; picking Robin is an act declaring you accept all of Robin's weaknesses and believe you can come out ahead by relying on Robin's strengths. If you believe the trade-off is not worth it, just don't pick Robin.
Also, consider enforcement. If you believe this infinite should be banned, put yourself in the TO's shoes. The match-up Robin versus Zero Suit Samus is being played at your tournament. An angry Robin player calls you over; he is down a stock versus the Zero Suit Samus player and on the respawn platform. He claims the Zero Suit Samus player did the infinite on him; the Zero Suit Samus player simply denies having done any infinite sequence and claims to have just significantly outplayed the Robin player. What do you do? I hope you quickly see that this hypothetical rule banning the infinite is forcing a TO in most common situations into a situation of just guessing who is telling the truth. We can't and don't monitor a majority of matches as they proceed; this is okay because the rules are "do what the game lets you do" and the niche rules against stalling (the hardcore kind like Luigi ladder in doubles or using infinites for the purpose of running the clock instead of getting a KO) are easy to enforce since you can stop the game, call over a TO, and have him watch and at least make sure no stalling occurs from that point forward which is generally sufficient. A rule like banning an infinite outright? You're just relying on the honor of the competitors to observe the rule and not lie about violations; this is a compromising position for a TO to be in, and the gains the game could prospectively have by not having the infinite in the metagame are far lower than the losses we risk by allowing these kinds of controversies over what really happened to flourish.
I do notice it's a lot of the newer and less experienced users who want this ban; I understand their thinking since this issue would seem to be one in which one thing no one likes (we all hate infinites) is just making the game worse. However, the large resistance more experienced players are offering is very purposeful; we've seen these kind of things play out in the past, and our past experiences inform us that overall we're collectively better off if we just accept these kinds of flaws in games and not try to correct them with rules. I hope our posts in this topic are convincing to some of you guys; I promise we don't hate Robin or love infinites. We just want the game on a competitive level to be the best it can be, and we know this kind of rule doesn't produce that result.
