At the 2% contained in feed, there is 
no (read 0) risk of any complications at all.
If your birds are exposed to dirt (i.e dust baths, scratching, pecking, being a chicken), they're already exposed to much higher levels of not only a few kinds of silica (3%-45% region depending), but other "harmful" substances.
Also, at 2%, even if your birds never touch dirt [which would be neglectful and detrimental for the health and well-being of the bird], their own dander poses more of a threat than 2% DE in feed.
I am very likely, the most anti-DE  person here. I'm pretty well read on it.

 and from my reading I will make the statement that:
2% in food, is not going to cause any issues, period. There's more risk in plain, ol', backyard DIRT and their own dander.
It won't control parasites.
It doesn't cure disease.
But it does keep feed from clumping, which can set off other feed issues.
If you have issues with it in feed, you can serve the feed wet, which nullifies any airborne dust.
But this not remotely a thing that anyone should be concerned about.
As is everything else,  the poison is in the dose.