Apple buying a toy company is a bad idea. The reason being Apple likes to design hardware themselves while Nintendo would have a weak output if they had to work on Apple hardware. There is no synergy. They’re both very succesfull because they have full control over what they want to do next with hardware and software.
I've always found Nintendo's stock price in any short term view (1 month, 3 months, even 6 months) to be an incredibly unpredictable thing. It suggests that their investors are very fickle, and that in turn suggests that actually, articles like this one do have an impact.
If you look at their price just before Switch announcement and compare it to today, then that tells you all you need to know. As to why it's dropped so much from last year, I honestly believe it says more about the people that have invested than Nintendo themselves. I mean, 2019 and 2020 have the potential to be enormously successful years for Nintendo. I've no idea why you would sell your stock in 2018. Seems crazy to me.
More specifically on topic though, if Nintendo didn't sell off the back of the Wii U (bare in mind all of their incredible IP had some of their series highlights on that platform, yes I'm including BotW in that) then I'm struggling to see any reason why they'd do it mid-way during the success of Switch.