I mean, there's a difference between being interested in him and saying "You brought us money, you can have a Geno costume, as a little treat." There is no public record of Square Enix even acknowledging Geno's existence, let alone supporting him for Smash. That's an incredibly stark contrast to Phil Spencer on Twitter literally saying he would support Banjo & Kazooie in Smash while leading the Xbox team that would directly have ties into getting them into Smash, especially at exactly the same time the Smash Ballot was starting, and then reconfirming that two additional times after the fact, and Square Enix literally never acknowledging the character. The absolute best case for Geno we can assume is pure neutrality on Square Enix's part. Square Enix gave him in a largely insignificant way to Sakurai to put in tertiary roles in Smash 4 and Ultimate when asked, but that's business and not inherently indicative of interest in him. They're as interested as the money given to them requires them to be based upon what we've seen so far.
I mean, difficult to obtain in that you still have to work with Square Enix on a character they don't really stand to benefit from on any level beyond the money they get from the Smash deal. Square Enix's dealings are generally still understood to be complicated affairs. I don't think Square Enix is stingy either and I think that's mostly an excuse Smash fans used for years to avoid more in depth conversations on Square Enix and what them in Smash actually means and requires. But I do think they would be considerably more willing to go through different hurdles for characters that directly benefit them and their brands in meaningful ways which again, Geno doesn't really do much for them. Square Enix not being stingy doesn't mean there still aren't additional difficulties in working with them and specifically trying to license content.
The obstacle to entry is truly just how small he is comparatively speaking. I say this as Geno fan, but like, the deck has always been stacked against him in the harshest ways possible. He barely brings a new universe to the game (of which, 3 of the 5 party members are already playable in Smash), he doesn't promote an active brand that Nintendo or Square Enix are in position to do anything with, he has no person in a fundamental decision making role supporting him at Square Enix and his sole representative that we know of at Nintendo isn't choosing DLC outright, he arguably had his absolute worst stretch of lagging popularity when he needed most in the ballot days, he's against some of the toughest competition imaginable because Square Enix has access to one of the most impressive starting benches in gaming, etc.
Like, if Sakurai could just have shoved him in the game, I think he would have, but other parties control the board. Nintendo has to commit to the idea of including him before they even get to Square Enix, who may balk at the notion of Geno as a fighter before other characters or maybe they're not comfortable with him being such a major part of their branding in Smash. Just because they got his Spirit doesn't mean anything. That doesn't make things any easier if they want him as a character by any means. All that means is Square Enix agreed to some deal to make him as a Spirit, nothing more, nothing less. If Nintendo and Sakurai want him playable, they have to do an entirely new process and then work with Square Enix to see if that's something they're interested in or not from the ground up since that's how licensing works with any project of this size.
It's just complicated for Geno and he doesn't have any of the positives that Banjo & Kazooie had going for them beyond being a fan request and having Sakurai take an interest in him in the past.
