This recipe replaces rare metals with aluminum, which is a much simpler recipe. I can understand that hiding the recipe for balencing purposes makes sense for space platforms, but it makes creating science on Muluna is really annoying as you have to ship in rare metals to create rockets.

I think that enabling that recipe, but only allowing it to be used on Muluna, would be a good compromise. It prevents space platforms from creating infinite processing units, but allows you to ship science from muluna without requiring any imports

No imports are needed, as you get rare metal ore from digging lunar regolith. Only 2.5% of the output will be the rare metal ore you want so you'll need to handle the unwanted outputs (probably by using inserters to void it all, since Muluna adds that).