How do I address the XBOX Enforcement team after an appeal was denied and the case was upheld?

Who are they? The Wizard of Oz? lol.. the entire system is a bit too autocratic. I hope they don't have something ridiculous like this in place for their next console, because it will be a MAJOR deterrent when choosing between theirs and Sony's Playstation
5.

you can only ask help on enforcement page..no other method..

He is correct. A case review is the only way to contact the enforcement team and you only get 1 review. Everything you do on Live has to follow the code of conduct/terms of service. Even though a game or movie may be sold through Microsoft, if you make a
reference that has something in it that violates those rules, you can be punished. Games/movies are rated for things like that, Live is not. So everything you do on Live must remain E for everyone.

If you want to speak to support directly, you can request a call back or chat with them at http://support.xbox.com/contact-us

Also, if you do decide to move to Playstation, keep in kind that they have similar rules on their service. The difference when it comes to bans is that they don't offer a way to appeal at all.

That's unacceptable. I was punished for something that made a reference to a film that Microsoft sells on their XBOX store, and they know this. They gave me a generic reason, and I know there's got to be another way to contact them.

If you are being honest in saying there isn't, I'd like to file a corporate complaint.

If the decision was upheld then that's it,the account remains banned & there's nothing you can do.

As you filed for a case review then that means 2 different people have investigated your case & came to the same decision.