Saying Wii U was a gen 8 platform and didn't have to beat 360/PS3 didn't exactly help that out...
360 didn't beat out PS2 but look how well it did, Megadrive didn't beat out the NES but that did well, the idea is not to beat out the previous gen it's to gain a strong footing in its current gen as the previous gen will be phased out and that's what Wii U didn't do in its head start.
I think he is talking about how poorly WiiU did when they took this secluded approach of only relying on themselves. 360 and Megadrive competed with PS3 and SNES and had many of the same games.
So when you look at WiiU as an 8th gen console, it was a collosal failure in that regard. And I don't think Nintendo can do anything about the 9th generation on their own either, outside of what they did for the WiiU themselves. No one else will make 9th gen games until the industry as a whole is ready to move forward. And if NX is only slightly stronger than PS4, then when the "real" 9th gen consoles come out, NX will be even further behind the other current consoles in terms of power than WiiU was, and we'll see problems in that area again.
So if we look at NX as a 9th gen console, it will likely be a failed one as well in that regard. I expect most of NX's games to be 8th gen titles + Nintendo's own games. Therefore I'll probably refer to it as Nintendo's 7th generation console, or one that joins the collective 8th generation a few years late.