I'm confused. Is this about buying, making, or a rules change proposal?
If it's a rules change, what is it? If it's requiring shutoffs on ALL racers, it won't bother me, but it will squeeze out some others.
The merits of shutoff in Combat can be defended, but the rule squeezed out so participation.
I bought some Russian F2A shutoffs. Good workmanship. But like all store-bought shutoffs, you need to engineer the model to fit the shutoff.