I had a similar issue with a ATL CP back in 1999. Refused a E-120 because of no working radar. Area forecast showed TP in the vicinity. I refused the airplane with out a radar. This former CP freaked out, and then made me and him fly the trip. (Removed the FO to prove to me that it was not needed) Of course we got a new radar control panel and blasted off.
In the end the radar was needed, but the action desire for you to fly an airplane with a perfectly legal deferral was the same. Stand your ground, you do not have to sign the dispatch release. One thing I learned from this is, be tactful and forceful. Do not refuse a jet on a company radio freq, and call them on the phone.
If they want to have administrative action on a pilot, so be it, but you have a moral and legal obligation not just to the yourself, but to your passengers and FAR's. They will get over it, but if they do not the grievance and arbitration process are great at resolving these sort of things.
The grievance and arbitration process are NOT great at resolving these issues. I can think of several cases where honest, well-intentioned pilots were hung out to dry. Not every time, mind you, but enough to know that you're rolling the dice when you choose to go through the process. Despite this, I strongly advocate standing your ground if you feel you're right. It's just as important for the 'next' pilot to back up the decision of the original pilot's refusal to fly. In my experience, backing up a fellow pilot's 'no-go' decision is extremely rare at the regional level. One does not have to necessarily agree with the pilot's decision, but just agree that every pilot does (and should) have the right-of-refusal. One day it might be you.