Whelp, here we go.
Android is an OS that is outside of Nintendo's control. If Google decides to make any major changes Nintendo would be forced to adopt them or stick with an older version.
Android is designed to be easily modified. Consequently, any user can hack their console and add software or modifications that Nintendo cannot condone, such as cheats for online games.
Android has security vulnerabilities up the wazoo and has to be updated monthly. Not even Android manufacturers can keep up (Except Blackberry's Priv; and Moto bowed out of timely updates). Do you really want to be installing security updates every month?
Android cannot be locked down. Any paid app on Google Play can and has been hacked so you can play it for free, even on devices the app was not designed for. Hell, I have the Blackberry Priv's app suite on my Moto X Play despite them supposedly locked to the Priv. Any game Nintendo offers for the console, even if they use their own app store, can be hacked and played for free - and even played on non-Nintendo handhelds (hardware permitting).
Android does not have efficient resource optimization. An errant app can slow down the system and kill the battery, and most users can't do anything about that.
To make a consideration worthwhile, Nintendo would need the Google Play Store and therefore comply with all OHA regulations (severly limiting how much they can lock down and secure the OS). If they do not have access to the Play Store, then it is completely pointless to be running Android in the first place because Developers will have to manually bring their apps to the eShop, so might as well add the step of converting to the OS that the console uses.
I'm aware that people have a vague desire for wanting android on their console, but Android and Nintendo are inherently incompatible. Any such discussion is purely nonsensical, with as much merit as wanting a fish as a Ferrari. To even talk about it is an insult to Nintendo's integrity and shows vast ignorance about how the company actually runs.