Hmmmh. Satch played with Deep Purple as a hired hand, he helped them out after Blackmore's departure. That puts him in favor with me (never mind how he's responsible for Steve Vai learning guitar, we all make bad choices). Chris Martin has a pretty wife. And a pretty voice. In small doses his band is bearable, but he probably doesn't even know who Deep Purple is. And he's more famous than me, so I hate him.
Still, even after listening to this side by side, it's a stretch. The Coldplay tune was immediately familiar with me (most catchy songs are) when I first heard it in my car stereo, but short of what he played with Purple, I've never heard any solo stuff by Satriani, so
I didn't know the Coldplay tune from him. That melody is not so idiosyncratic (or musically ambitious) that you would need to bore yourself with Joe Satriani CDs to come up with it.
He could learn a thing or two from Coldplay's arrangements though.
Uwe
PS: No good things to be heard from Gwyneth's and Chris' marriage lately (down, Dave, stay calm!). But you know how women are. Has she been provoking him by listening to Joe Satriani at home?