Understood. I misinterpreted your intent.
Ideally I think there should be no distinction in availability for LA tools, just a restriction on where they operate. That’s how darktable is designed.
And as I’ve posted elsewhere I think an adjustment brush would be a hugely helpful feature. It’s possible to partially approximate it in darktable but not completely (e.g. the change to the mask isn’t visible until the stroke is ended, not as it’s drawn in real time). But that’s another topic.