I had the same problem with the salesman not fully explaining their policy up front, but it was really my fault for not being clear that I was planning to do a PRS copy. I don't fault them for not wanting to copy anybody. I understand that they got a few calls from PRS when their VIP model was introduced.
Warmoth has had to cut back on the "custom shop" aspect of their business as they've morphed into more of a production house, in order to stay competitive in the marketplace. Used to be I could drop by their shop and talk face-to-face with them and put my hands on the actual product. Now it's just telephone/internet sales. But the quality is still excellent. I ended up doing my own mods to their standard VIP product to get the look I wanted.
Like I said, even if you draw it up, they won't do it if it's a copy, or close to it. The reason they insist on a hard copy full-scale drawing from you is to avoid communication problems that might result in you being dissatisfied with the final product. I'm guessing they learned this one the hard way.
I found a decent headstock pic and resized it to match the nut width, then I tweaked it from there until it looked right. It wasn't a straight-on shot, but it worked for me - mine's not an exact copy anyway. If you need an exact replica, best get a buddy to distract the sales people at Guitar Center while you trace the outline. I don't think they'd care all that much anyway.
It's best to get the tuners lined up so you get a straight path from the nut slot. Takes a bit of measuring and fiddling to get them just right. Again, make sure you reference the locations off your center line.
Mike