He's "taking a stand against Apple", but ISTM the real offender here is about the company that built an app with his code and submitted it to the store in breach of his license.
Of course reading motives into people's heads is prone to error, but it's implied by his choice of the GPL...
You cannot force GPL down Apple's throat. It is their application store. If their terms are not compatible with your license, change your license or live with it. By picking the GPL you are excluding some distribution venues.
In the meanwhile, the VideoLAN project is still endorsing the iOS application on their website. So, they are sending copyright infringement notices, while at the same time encouraging people to buy it?
Which is exactly what he's doing. He could have let the original infringement slip quietly by, but instead he's using it to make a political point. Everybody loses short term, but he's hoping for long term gains.