Bizarre question regarding Gligar, Dig, and Earthquake

[Every Breaking Wave]

So today I was in the Battle Tower in Pearl when my opponent's Gligar used Dig. I switched to Torterra, since it's four times resistent, and also happens to know EQ. But then I wondered; normally Gligar is immune to ground attacks since it's part flying. But EQ hits Pokemon that are using Dig. Would an EQ on a Gligar that's in the midst of using Dig have any effect? Or is it still immune?

 

[Geodude]

Still immune.

 

[GuitarHero]

Yeah, this is one of those strange cases in the game that I think should be fixed. I ran into the same thing...
Opponents Vibrava used Dig!
Blastoise used Earthquake!
Vibrava's Levitate makes ground moves miss! (or something like that)

I was like wtf, its underground?!

 

[Shinx3000]

I got the same thing with a vibrava too, it should be fixed, So basically any pokemon that is a levitate or part flying that uses dig, no ground moves can affect it? Thats not right

 

[Cheesus Is Lord]

I use that to my advantage in doubles. No one expects a digging Ninjask! And it has the speed to pull it off, too.

 

[Geodude]

And Torterra is not 4x resistant to Dig, just 2x. Ground does normal damage to Ground.