Indeed. Daniel Graystone is the only person who knows about them meeting.
After I joked about it I realised it might not be as strange as I first thought. Daniel is the only person we know knew about the meeting apart from Amanda. More importantly, if it wasn't Daniel who the hell was it?
It couldn't be STO, they only found out the band was missing later on and they didn't even suspect Amanda Greystone was the spy. It can't be the GDD double agent, he would have contacted the STO by now. None of the Adamas would have had a reason to be there, nor a reason to shoot unless they'd been put up to it by Daniel. Zoe and Tamara are stuck in V-World, Lacy isn't even on the planet, who's left?
About the only other credible suspect I could think of apart from Daniel and the GDD double agent is Barnabus and he's supposed to be dead.