Lets suspend reality for a second, what would having the mint apply a matte finish to a dime blank prove? We already know the mint can apply different finishes to blanks as they have produced matte coins for sets. All that would prove is that the mint could do something that we already know it can do. It would in no way prove that your coin was in fact produced by the mint and not altered later. And how is a mint employee expected to verify anything (and what distinct detail do you expect them to review) all that employee can do is look at your coin and render an OPINION, which is what many experts have done via photos and you continue to deny those opinions. And what happens when you disagree with the mint employee's opinion, what tests will you demand then, seriously.
Now back to reality because in reality the mint is not going to do what you want, why because its pointless and they are not in the business of performing such "tests". There are no meaningful tests that can be done, the only way to prove your theory is to find mint records that show where such a finish was applied to one or more dimes at the Denver mint in 1993. But without such documentation you will never be able to prove its anything other than a post mint experiment worth 10 cents.