There is a workaround which sort of simplifies setting up custom mutes for User styles, though.

You don’t need to go to the full Style Editor, you can mute style Parts with the Makeup Tools and overwrite the original user style (that way, any Performances that use that style won’t have to be reconnected to the edited style). It’s a simple job, takes a few seconds.

Now, you can load that style into a Performance that has all Parts enabled, but because Makeup Tools has muted the Parts, nothing will play on the muted ones. You can then load any style into the Performance afterwards, and they will play normally.

Your only issue would be if the style you want to mute certain Parts also needs to be used with the full mix occasionally. In this case, you’d save the edited style with a new name so the full original is still available.

Other brands may let the style set up the registration, but the Roland Way has always put the Performance as the master..!