Also can we remember that Sakurai specifically said in the K. Rool/Simon direct column that he went off the ballot for newcomers?
I doubt that Chrom, Dark Samus, Ridley, Isabelle, Daisy, and Richter did amazingly. Chrom and Dark Samus he mentioned as popular, Ridley he's been trying to fit in the roster for a while now, Isabelle is the face of Animal Crossing, Daisy is likely the same boat as Chrom/Dark Samus, and Richter is just more popular in Japan than Simon.
Pretty sure the only notable placers we got so far are K. Rool, Simon, and Inklings. I doubt those were the only ones he chose off the ballot.
Which leads me to believing Grinch far more than insiders. I doubt he'd take a look at Geno + Isaac going "Wow! These guys sure are popular, they'll want them as Assists I bet!" Straight up a ridiculous notion at this point lol