Just in case you are having trouble understanding the Grammy nomination process and how Al Walser gained a Grammy nomination in the same category as Skrillex, SHM, Calvin Harris, and Avicii then check out these articles written by Rolling Stone, Dubstep.net, YourEDM, and Vice.
But my favourite source was hearing Al Walser talk about it himself in this 47 minute interview with Dubstep.net:
Al Walser talked frankly to Dubstep.net on how he gained the Grammy nod, and to my surprise, I actually ended up enjoying his candour and the way he conducted himself in the interview. In the past 24 hours I've learned more about the Grammy nomination system than I ever have in my life.
*Update: If you are unhappy by this nomination then you should be upset at how the Grammy nominations are made, not Al Walser.
*Update 2: Billboard.biz offers up even more details oh how Al Walser received his nomination.