Nintendo aren't that stupid.

But is this an example of bad publicity?

I was going to say the same thing but barkley has a different opinion, he finds that to be stupid! :(

I hope there's a new Mario Party, so then Nintendo will give my Wii U life again.

They said Zelda would be the only playable game there, they never said they wouldn't show other games

Common sense.
It didnt make any sense to me that they would only do Zelda at E3, if they also have other games.
Hell even just 3DS games, why wouldnt you want to show them off?

Making it seem as if you have nothing to show to generate negative discussion doesn't sound like a good business move to me.

They had cancelled the Pokemon GO GDC panel earlier

I bet Gamefreak pushed for the E3 presence. Putting the pokemon mobile game in the spotlight at E3 will sure to ameliorate Nintendo E3 reputation for this year thus far. Really reminding people that it's actually happening will have people losing their minds in a good way if they didn't already know about it.

Only to surprise everyone with more announcements at the last second.

So Nintendo didn't skip E3 after all.

Good. They need this.