If I was the DPE, I would have made sure to CYA myself too, although without the attitude and issues you had. If it's an area that I didn't experience regularly, it's possibly not something I can sort through in just a few minutes to see if I can do it or not. There have been certs and ratings issued improperly due to hasty decisions or not properly researching it.

Luckily, I'm not a DPE, I'm the guy that tells the DPE what to do, and if after doing the above research I mentioned, I found that there was nothing preventing the issuance, I'd tell them to go ahead and do it.

Sounds like this guy has some issues admitting he is wrong and handling their applicants in a professional manner.

If you are arranging a checkride and doing something that isn't the "usual" way they see applicants, you might want to ask them first about your specific situation, rather than showing up on the day and presenting something to them that they don't usually encounter.