>> He still thinks the right way to do efficient data access is flat files. <<
Efficient for what, the machine or the human?
>> And seems to believe if something is not how he already does it, it can't be right. <<
You have to decide what is more important: money, or the right to tell someone they are wrong. I am afraid that they are probably mutually exclusive. Sometimes I want to say, "I will take a 10k/yr pay cut to gain the privaledge of telling you when you are stupid." Or negotiate frequency of stupidity notifications per K reduction.
I once had a boss who actually liked to hear my opinion on things (most of the time). Those are rare. Most want smiling Yes-men.
But, naming conventions are a personal thing. I have my own preferences, but would not make somebody rewrite a bunch of stuff before they knew the shop conventions. If it was so important to him, he should have said so up front.
I would probably want prefixes for views and stored procedures, but not for tables.