Hide theme from admin UI when using streams

We've created a theme as an extension to antimatter utilising the streams feature to overlay the necessary parts.

How can I hide the theme from the admin UI so that no one can accidentially activate the standard antimatter theme?

I'm afraid there is no option to do that currently.

I need this feature as well. I wonder if we could add a config in the theme blueprints.yaml like "hidden" or "available" so the theme can remain as is just be hidden within the Admin UI. Another alternative is to make the Themes pages hidden within the Admin.