Scotch Broom field turned into a permaculture orchard.

My question is will a scotch broom field be a good spot to establish an orchard?

Here is my logic. Scotch broom is a nitrogen fixer and will build soil well. But it is also very aggressive and hard to get rid of. The reason I came up with this idea is that I listened to Pauls short snippet about scotch broom (https://permies.com/t/16089/podcast/podcast-scotch-broom-critical-thinking) and he said that the only thing that can choke it out is a tree layer. Now, I see a bunch of problems with this but would love your guys insight.

I would guess it depends on where you are and the conditions of the site.

I have seen it work on a small scale (approx 1/2 acre).
On a slope adjacent to the road, here in western Oregon.
It wasn't a permaculture installation, but they used some permaculture methods.

Water Harvesting - A road was installed, roughly on contour across the slope
Chop & Drop - The scotch broom was cut down, some of it was burned, some just left in place
Water Retention - A large quantity of mulch was put down
Layers - Multiple types of trees and shrubs were planted, mostly berries and fruit

It took about 3 or 4 years, and as I recall they would cut or pull the new broom plants up every spring.
Now the broom appears to be mostly all gone from the site.

I suspect it was a combination of the increase in water, improving the soil, and increasing the shade.
Seems to me if you did something like this in a more dedicated fashion, and chopped/dropped early spring before they bloomed...
you should be able to do this even quicker.

Is about an acre and a half in Western Washington. I was thinking exactly what you said other than the earthworks. The piece of property has a slight slope but holds water well. There is plenty of mulch that is helping with that.

"It took about 3 or 4 years, and as I recall they would cut or pull the new broom plants up every spring.
Now the broom appears to be mostly all gone from the site."

My only thought about this is that I heard that the scotch seed can stay dormant ready for germination for years, this is kind of like the mother nature knows best saying. If the scotch comes back then we know there is a problem that needs to be fixed. Is this a valid thought process?

Sounds to me like scotch is actually a pretty awesome "noxious weed".

Check the soil first! Scotch broom is usually an indicator of poor soil (since it doesn't NEED that nitrogen..) -- see how far along the soil has come before trying to establishing nitrogen consumers. If the soil is still poor, chopping once and planting in black locust will start to shade the scotch broom out..

My only thought about this is that I heard that the scotch seed can stay dormant ready for germination for years, this is kind of like the mother nature knows best saying. If the scotch comes back then we know there is a problem that needs to be fixed. Is this a valid thought process?

Well, kinda. It's not always an indicator of poor soil either, I still have seedlings popping up in my fertile veggie patch. If new seedlings pop up, it's because there's enough light getting to the soil to trigger germination so in an orchard that could indicate a problem. Yes, the only thing that I've found that can choke it out is trees. However, it doesn't pop back from it's roots when you lop it off at the ground which is incredibly more wonderful than the blackberries which pop back as soon as you turn around. Once you get your clearing and planting done, it's not so hard to lop off the occasional seedling. As long as you get plenty of ground cover under your fruit trees, and you walk through with pruners on occasion, it shouldn't be too bad. Also, for what it's worth, my goats love scotch broom. It's all gone from their field so the stuff that pops up in other places I toss to them. I don't know if there's room in your plan for a livestock component, but it might be worth considering, though goats and fruit trees definitely don't mix.