Looks like users on that thread are calling bullshit on Graphene for claiming GPL violations.

I'm not sure why they don't just sue Google if they feel so strongly they're in the right. Crowd fund the legal cost if they need to there will be plenty of their users willing to give them some money to stick it to Google. Use their Motorola money if they want. They expect a win and agreement in court so it's a no brainer.