The Roadster HPC is open to any and all Roadster owners who needs to charge. I spoke with the manager Alex Henry yesterday, and he said he is more than happy to move his car if there is no space!
Alex has always been sensitive to the needs of other Roadster owners and quick to help out if he can. He also recently acquired a CAN SR (for himself, it's not the store's) so he has a little more flexibility for where he can plug in.