And ironically people still complain.I don't think it's that complicated. Obviously they'd have to resolve the artwork issue before the game goes gold so Monolith Soft know about it and Smash well in advance. Their options are let someone else fix the art work, fix it in-house or let it get cut. They picked the second option and sent it off. That's everything relating to Smash Bros done - their talks with Sakurai are over.
Everything after that point though? Purely Monolith Soft acting on their own.
"Hey, we should add it to the game proper as a tie-in! We can already do costumes."
"Yeah, we'll have the NPC in XB2 that gives it to you make tons of Smash references!"
"And we can make the Torna NPC that gives it to you dance like beloved gaming icon Tatsu, as a hint to who the Xenoblade character in Fighter Pass 2 will be in 3 or so years!"
Make it, ship it, soak up more of the Smash attention and curb the inevitable censorship complaints (Xenoblade X got hit with so many that Takahashi had to explain in an interview that he didn't mind the changes, so they definitely know how people feel about it).
That's fair. Though I imagine they still had to get the green light even if they were acting alone. That doesn't have to mean anything, just that they got permission to slip in an extra bit of content.
And, wait, people think a Tatsu dance means something? Granted, this is the community that thought a purple chair was apparently some sort of sign or something. Some may have unironically claimed that too.