Forum:Infernity Guardian question

Hello I've got a question regarding on when Infernity Guardian's effect works.

So I was dueling someone on DN and I attacked a face down Infernity Guardian with a Blue-Eyes White Dragon while he had no cards in his hand.

Now Infernity Guardian says, while he's face up he can't be destroyed by battle or card effects, however I'm wondering if he's flipped face up by battle and the atk points are higher than the defense points while the opponent has no cards in the hand is Infernity Guardian still safe?

I'm pretty sure this is self explanatory but while Infernity Guardian is face up in defense mode and attacked by a Red Dragon Archfiend he survives as well right?