To be honest, this fits with news that we were in talks with Blackpool right-back, Danny Coid, which someone posted previously. I suspect we got wind of Calderon's change of heart and started to look elsewhere - hence why it all went so quiet.
Calderon's spat with Brighton was that he wanted to hear other offers before making a decision, not that he wouldn't sign what he was offered. Maybe we didn't value him quite as highly?