Disclaimer: This is a weak theory with little to no evidence to back it up. It's basically a wild guess, so don't take this seriously, but do take the TL;DR seriously.
Aside from what Shaya said, I'm going to go out on a limb - pun intended which will make sense as this post ends - and say it might have to do with Falco's "elemental nature". In terms of normals, Falco only has dash attack, Ftilt, Up Smash, Down Smash, Uair, Bair, Dair, and his getup attacks as "normal", "no", or "hit" elements. Everything Falco has from jab 1, jab 2, rapid jab, rapid jab finisher, Utilt, Dtilt, Side Smash, Nair, and Fair are all "slash" elemental. That's 9 moves or 6 if you count jab as one move instead of its parts, but that wouldn't make sense for characters like Ike and Shulk whose jab is made up 2 normal hits and 1 slash hit. The rest of his 7 commonly seen normals and 3 getup moves are just normal moves. Either way, about half or a third of Falco's moves are slash elemental and what is slash commonly associated with? Sword users.
Elements do affect gameplay with fire being the easiest to see where it will instantly blow up explosives while with non-fire moves, it takes a couple of hits to disturb them. Electrical moves tend to have hit lag modifiers and darkness tends to be just stronger. If, this assumes if, elements do more than just visual, audio, and some gameplay, Falco technically is a sword user without being one if that makes any sense. Charizard, Bowser, and Brawl Wolf also have slash element moves, but theirs is few or doesn't seem to be so like Charizard only has jab 1, jab 2, jab 3, Up Smash?, and Fair and except for Up Smash, I don't know if any of them are disjointed. If they are, they might be really small like his claws are disjointed, but that's not much compared to Falco's entire wings.
Assuming elements play a major role, Falco has access to a lot of stupid disjoints because of how the game's programmed. I mean, are you seriously going to give Falco his own element that only has different visual and sound effects? For Lucario, it makes total sense since it has a factor to his gameplay, but Falco? It'd be a waste of time. Anyway, this might have had a side effect where some of Falco's moves are disjointed by the game's programming.
Assuming so, Falco has 9 disjointed normals, 1 of which, Side Smash, is transcendent, 1 intangible move: Down Smash, and I should check, but his Up Smash might be partially invincible like Fox's. Including U-throw, B-throw, and D-throw's laser parts, Blaster, sometimes Falco Phantasm and Fire Bird, and Reflector, then Falco has 16 disjoints, 6 transcendent, 1 intangible, and potentially 1 partially invincible move. That's actually kind of stupid considering he's not a sword user... Welp, more Leona Heidern parallels.
At the same time, Fair is disjointed which is noticeable with the landing hit. If it was disjointed on his beak, then that's kind of a small disjoint.
TL;DR: Falco is just one weird bird.