Here's the thing. If he tried getting Geno in Brawl, why did he skip over Geno for Cloud in Smash 4? Geno obviously had a lot of support, and his inclusion would certainly make a lot of people happy.
I'm sure there's plenty of characters Sakurai would like to see, but just because he publicly makes a comment on a character during one Smash game doesn't mean they're guaranteed in the next game. Yes, Geno is popular, but so is Dixie, and Impa, and Waluigi, and Captain Toad, and Bandana Dee, and Elma, and dozens upon dozens of other more relevant choices.
People need to understand that popularity itself does not gauge how likely a character is. It took Ridley nearly two decades to get in Smash, and he was consistent in both popularity and Metroid appearances. Would Geno, a random Mario character who hasn't technically done anything noteworthy since his debut in a spin-off game, really be one of the few newcomers Sakurai chooses to add for this Smash? Personally, I don't think so.