Switch needs an enormously strong fiscal Q3 to come anywhere even close to Nintendo's bold forecast. This isn't exactly the best way to start that, particularly since these October numbers include the Smash Ultimate bundle. Being down YoY when last year was hindered by stock shortages for the Switch isn't something that should be made light of.
Remember, we already know from Nvidia that Nintendo is channel stuffing this quarter so its not about how much it sells to consumers as the pipeline already has the Switch's available. That's why they haven't revised their numbers.