A lot of times when translating articles, and going for click bait headlines, things get mangled. I was searching for where Sakurai may have said he was not making another smash game, and I can’t find anything like that. On the contrary, I am seeing articles saying things like he can’t see another smash game happening without his involvement: https://www.si.com/esports/fgc/new-super-smash-bros-game-sakurai
But regardless, it’s easy to get burned out on something and feel like you never want to touch it again. Then a few years later your feelings on the matter change. It’s happened to me. Doesn’t mean someone “is full of shit”.
The game was in a pretty rough state when they relaunched it, but they have been slowly improving it a bit at a time (it often feels like 2 steps forward, 1 step back). I feel like the game is in a pretty good spot though. I enjoy it and am looking forward to season 4.