I'm not sure how long it takes for Sakurai to develop Smash characters, but Three Houses did release around six months ago, so it's not unreasonable to assume that the decision was made after Three Houses blew up.Sakurai didn't know the game would had been successful or not when he decided on another Fire Emblem character.
It was all speculated/assumed.
I guess it's cool knowing time isn't a huge factor with his decisions if he can pull stunts like this. Now my wishing for recent games can't be unfounded by "that game just came out".
Officer Howard can make it in <3